American Board of Surgery In-Training Examination (ABSITE) Practice Exam

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• How can paraneoplastic hypercalcemia be distinguished from primary hyperparathyroidism?
• What is the treatment approach for a pyogenic abscess?
• What is the surgical approach for esophageal leiomyoma if surgery is necessary?
• What are the two diagnostic methods for echinococcal abscess?
• Which stage of T staging indicates invasion into adjacent organs or structures?
• What are the four boundaries of the femoral canal?
• Which organs are at increased risk in patients with HNPCC besides the colon?
• What is an initial treatment strategy for hypercalcemia?
• What vitamin deficiency is commonly associated with Total Parenteral Nutrition (TPN)?
• What type of fatty acids are emulsified to micelles before absorption?
• In the context of renal arteries, what distinguishes the right artery from the left?
• How much bile is lost daily as a percentage of the total bile pool?
• What is the risk for associated malignancy in patients with Barrett's esophagus and high-grade dysplasia?
• In the treatment of gastric tube reconstruction after esophagectomy, what is the primary arterial supply?
• What is the function of renin in the body?
• What mediates Graft vs Host Disease (GVHD)?
• Which nerve wraps around the head of the fibula and lies laterally below the knee?
• What is the primary effect of angiotensin II in the context of the renin-angiotensin system?
• What is a hallmark characteristic of focal nodular hyperplasia?
• What is the treatment protocol for gallbladder cancer when T1b or higher?
• Where is cholecystokinin (CCK) primarily produced?
• What is the treatment for cholangitis?
• What is the optimum calorie:nitrogen ratio recommended for protein synthesis?
• In what area of the pancreas does the highest concentration of bicarbonate secretion occur?
• Which tumor is most commonly associated with the kidney in pediatric patients?
• What is the scoring range for risk factors in the Goldman Index?
• Which of the following factors shifts hemoglobin's oxygen affinity to the right?
• What complication should be avoided via biopsy in patients with esophageal leiomyoma?
• Which tumor is most commonly associated with catecholamine-secreting tumors in children?
• Which sign on an EKG is most associated with postoperative myocardial infarction (MI)?
• What is the most common site for ectopic pheochromocytoma?
• What regulates the characteristics of the migrating motor complex?
• What two benefits does the intra-aortic balloon pump (IABP) provide when it inflates?
• In patients with small bowel obstruction, which symptom typically indicates a more serious condition?
• What is the percentage risk of developing pancreatitis and cholangioCA from choledochal cysts?
• What are the classic signs associated with VIPoma?
• What is the most common solid tumor in pediatrics?
• Which chemotherapy agent is known to lead to pulmonary fibrosis?
• After one postoperative day, a patient presents with a fever of 104°F and grey wound drainage. What organism is most likely responsible?
• In the context of Lynch syndrome, which genetic alterations primarily affect DNA repair mechanisms?
• What is the primary difference between decorticate and decerebrate posture?
• What is the most common cause of cholangitis?
• What muscle does the external branch of the superior laryngeal nerve innervate?
• What is the origin of the inferior parathyroid gland?
• What is the follow-up procedure if carcinoma is identified in permanent section of a Hurthle cell neoplasm?
• In which part of the gut does motilin primarily exert its effects?
• What should be administered after the treatment of ITP to prevent infections?
• How long after splenic artery ligation should platelets be given?
• Peutz-Jeghers syndrome is associated with which of the following cancers?
• What is the common presentation of focal nodular hyperplasia on a liver scan?
• What are the primary reasons for choosing surgical intervention in hyperthyroid patients?
• Which side effect is primarily associated with Adriamycin (Doxorubicin)?
• Which condition is characterized by hypertension, hypernatremia, and metabolic alkalosis with a renin-aldosterone ratio less than 0.015?
• What is the management approach for a tracheoesophageal fistula?
• What is the importance of monitoring the renin-aldosterone ratio in Conn's syndrome?
• Which class of drugs are vinca alkaloids derived from?
• What type of liver resection is performed for segment 1+2?
• How many levels are identified in the T staging of colon cancer?
• Which of the following genes are associated with Lynch syndrome and are primarily involved in DNA mismatch repair?
• What type of fracture is most commonly associated with radial nerve injuries?
• For non-high grade Barrett's esophagus, what is the recommended management approach?
• Which of the following treatment regimens is typically used for intermediate to high-risk GIST patients after tumor resection?
• For patients with atypical ductal hyperplasia, atypical lobular hyperplasia, or LCIS, what is the most appropriate treatment approach?
• If a barium swallow shows a condition that is not achalasia, what is a likely diagnosis?
• In the presence of a testicular mass, what is the recommended surgical procedure?
• What is the treatment of choice for varices associated with splenic vein thrombosis?
• What malformation is often associated with gastroschisis?
• What preparation is required for an I-131 scan?
• What surgical approach may be considered for patients with LCIS who choose bilateral mastectomy?
• What substance fuels coloncytes derived from bacterial fermentation?
• True or False: Malignant hyperthermia is more common in children.
• What condition should be suspected in a patient experiencing chest pain, fever, and respiratory distress after emesis from a large meal?
• In treating upper GI MALT tumors, what is the first line of treatment?
• What is the most common benign hepatic tumor?
• Where do the renal arteries arise from?
• If a patient is unable to lower their arm, what position might they hold their arm in if the axillary nerve is compromised?
• Which circulation is responsible for the majority of bile reabsorption?
• In which group of patients is ketamine contraindicated?
• Which of the following represents a treatment for echinococcal abscess other than surgery?
• What does the Parkland formula help determine in burn management?
• When should surgery be considered in the treatment of an amebic abscess?
• What methods are primarily used for staging colorectal cancer, particularly for T and N stages?
• In the case of a minor CBD injury during laparoscopic cholecystectomy, what is the proposed treatment?
• What is the treatment approach for parathyroid carcinoma?
• Which symptom commonly follows the initial neurological symptoms of lidocaine toxicity?
• What are three common presenting symptoms of amebic abscess?
• Which branch of the gastroduodenal artery supplies the superior pancreaticoduodenal region?
• What chemotherapy drug can lead to neutropenic enterocolitis?
• Where does the external branch of the superior laryngeal nerve travel?
• What is the first test recommended for the diagnosis of a solitary neck mass?
• What is the percentage of phyllodes tumors classified as malignant?
• What are two surgical options for treating 4 gland parathyroid hyperplasia?
• What is essential for managing a patient receiving TPN to avoid complications?
• What is challenging about diagnosing a Hurthle cell or follicular neoplasm?
• If an abnormal fallopian tube is found during an appendectomy, what is the recommended course of action?
• Which type of groin hernia is most commonly found in women?
• For managing deep vein thrombosis (DVT) in pregnancy, what is the recommended treatment?
• A pleural fluid pH below which value is indicative of esophageal perforation?
• What complication is commonly associated with total parenteral nutrition (TPN) and enteral feeding?
• What is the most common cause of low phosphate levels in hospitalized patients?
• What is the primary cause of hyperacute rejection in organ transplantation?
• What is the scoring for GCS eyes?
• How does PEEP affect pulmonary vital capacity?
• What clinical finding is associated with low blood pressure and high end-tidal CO2 during laparoscopic surgery?
• What triggers the release of renin from the juxtaglomerular cells?
• In what demographic is hepatic adenoma most commonly found?
• What is the primary treatment for polyps associated with Peutz-Jeghers syndrome?
• What is the main risk associated with hepatic adenoma?
• What is the contraindication for lung resection based on preoperative resting pCO2 levels?
• What are the two primary functions of angiotensin II?
• What is commonly the second symptom experienced in lidocaine toxicity?
• What is the primary indication for a mastectomy or breast conservation therapy (BCT) followed by chemotherapy in breast cancer patients?
• What is an exocrine effect of cholecystokinin (CCK)?
• How can the common peroneal nerve be injured?
• What characterizes Plummer's syndrome, and what is the recommended treatment?
• What is the effect of medialization of the vocal cords in recurrent laryngeal nerve injury?
• What is the most common presentation of blunt myocardial injury?
• What is the recommended dose of protamine for reversal of 5000 units of heparin intravenously?
• What are the primary symptoms of cholangitis?
• Which procedure is essential for managing familial adenomatous polyposis?
• What is the recommended initial treatment for T1a gallbladder cancer?
• What veins and structures does the left renal artery pass behind?
• What syndrome is characterized by autosomal dominant inheritance and a primary feature of right-sided colon cancers without polyposis?
• Which age group is most commonly associated with neuroblastoma?
• Which cytokine is responsible for the hepatic acute phase response?
• What is a common treatment option for echinococcal abscess?
• What is the reason for performing a gastrojejunostomy rather than a stricturoplasty in Crohn's disease?
• What is the most common cause of small bowel obstruction during pregnancy?
• Which medication follows alpha-blockade in the treatment order for pheochromocytoma?
• What is the recommended screening for a patient with abdominal wall desmoid tumors?
• How is the risk stratification for GIST classified?
• Which condition has the highest score on the Goldman scale and indicates the worst prognosis?
• What is the expected enhancement pattern of focal nodular hyperplasia during CT arterial phase?
• What is the most common cause of a painful gastrointestinal bleed in children?
• True or False: Ketamine can be classified as both an analgesic and an amnestic.
• What is the most common cause of duodenal obstruction in children under 1 week old?
• What percentage of all gastrointestinal malignancies does GIST comprise?
• What injury is most likely associated with an inability to extend the wrist and MCP joints?
• What is the pulmonary vital capacity?
• What additional treatment might be required for steroid-resistant cases of ITP?
• What is the typical treatment approach for a carcinoid tumor in the rectum?
• How does parathyroid carcinoma commonly present?
• What classification of tumor does GIST relate to?
• What are the components of scoring the Glasgow Coma Scale (GCS) motor response?
• What effect does pure norepinephrine have in patients with extra-adrenal pheochromocytoma?
• Do all paraesophageal hernias require surgical intervention?
• What percentage of bile is reabsorbed daily in the body?
• What is the initial biopsy type performed for extremity sarcomas if the tumor is less than 4 cm?
• Where is the highest secretion of bicarbonate (HCO3) in the body observed?
• How is the GCS verbal component scored?
• Which patient population is at the highest risk for overwhelming post-splenectomy infection (OPSI)?
• What percentage of patients with LCIS have synchronous breast cancer?
• Which nutrient is considered the primary fuel for cancer cells?
• What are the breast tumor indications for sentinel lymph node biopsy (SLNB)?
• What is the initial treatment for patients with early Boerhaave's syndrome?
• What complication can happen due to a giant liver hemangioma in children?
• What is the first-line treatment for GIST, and what type of surgery is typically performed if needed?
• What treatment is indicated for gastric outlet obstruction due to MALT lymphoma?
• What symptom is associated with a score of 10 points on the Goldman Index?
• What is the recommended treatment for Barrett's esophagus with high-grade dysplasia?
• What condition results from an injury to the common peroneal nerve?
• What ions does aldosterone primarily cause to be retained or lost in the urine?
• Which organism is NOT typically associated with pyogenic liver abscess?
• What two signs are particularly suspicious for parathyroid carcinoma?
• What factors indicate a high risk of recurrence in GIST patients?
• A patient presents with a pelvic fracture and a positive diagnostic peritoneal lavage (DPL). What is the recommended first surgical intervention?
• What is a critical circumference criterion for transanal excision?
• How is the decision made between performing an abdominoperineal resection (APR) and a low anterior resection (LAR) in rectal cancer?
• The cremasteric muscles originate from which muscle layer?
• What is the best method to predict the risk of bleeding in patients?
• Which of the following is NOT an indication for surgery in hyperthyroidism?
• In cases of VIPoma, what electrolytes are typically affected?
• What is the mechanism of action of aldosterone?
• Which chemotherapeutic agent is associated with severe peripheral neuropathy?
• What is the earliest and most specific sign of malignant hyperthermia?
• What is another name for phyllodes tumors?
• What is the percentage of patients for whom dumping syndrome is unresponsive to dietary measures?
• In liver surgery, how can the right or left hepatic artery be addressed if necessary?
• Which factor is considered the most important prognostic indicator for melanoma?
• What is the most accurate method for diagnosing traumatic aortic arch injury?
• Which scale is utilized to correlate cardiac symptoms with perioperative complications?
• What is a defining characteristic of focal nodular hyperplasia in the liver?
• Which myeloproliferative disorder benefits from splenectomy due to extramedullary hematopoiesis?
• What imaging modality is the diagnosis of choice for liver hemangioma?
• What is a characteristic finding on a PA catheter in a patient with acute myocardial infarction?
• What should be the first step if only 3 parathyroids are identified in a case of 4 gland hyperplasia?
• What is the primary action associated with motilin?
• What is the main source of energy for colonocytes?
• What are the two primary routes for pyogenic liver abscess?
• What is the treatment for Frey's syndrome?
• What is a common cause of biliary infection leading to a pyogenic liver abscess?
• What should be done if the appendix appears normal during an appendectomy but Crohn's disease is present?
• What is the role of Sunitinib in the management of GIST?
• What symptom is commonly associated with injury to the superior laryngeal nerve?
• Which type of thyroid cancer is known to spread hematogenously?
• Which nutrient is poorly absorbed in achlorhydria?
• How is a Morgagni hernia defined?
• What are the treatment options available for a breast mass after neoadjuvant therapy?
• In which patient population is splenectomy associated with significant risk due to thalassemia?
• What is the best method for diagnosing spinal injury in an awake trauma patient?
• What is the most common cause of death in patients with postoperative acute renal failure?
• What is one advantage of low molecular weight heparin (LMWH) over unfractionated heparin?
• What is the most common liver tumor in pediatrics?
• When do patients with sickle cell disease typically require splenectomy?
• What is a mandatory treatment for Lobular Carcinoma In Situ (LCIS)?
• What is the first sign of lidocaine toxicity?
• What is the most common complication of an epidural?
• If malignancy is uncertain in a Hurthle cell/follicular neoplasm, what is the recommended treatment?
• What is the primary composition of bile in terms of percentage?
• How does the location of Hodgkin's disease affect its staging?
• What is the primary cause of resistance to aminoglycosides?
• What is the main type of inheritance found in HNPCC, and what is its primary cancer feature?
• How does the gallbladder concentrate bile?
• What is the lifetime risk of developing breast cancer after a diagnosis of LCIS?
• In cases of right heart failure, what changes would you expect to see on a PA catheter?
• What is the first step in managing hypercalcemia?
• What is the first line treatment for an amebic abscess?
• What is the most common cause of infection in vascular grafts?
• What is the sequence of treatment for MEN-1 with hypercalcemia and a gastrinoma?
• What is a significant exception for platelet transfusion during splenectomy?
• What is the primary action of prostacyclin A2?
• When is motilin released in the body?
• Which tumor is the most common in pediatric patients?
• What genetic pattern is associated with Peutz-Jeghers syndrome?
• What is the first-line treatment sequence for inflammatory breast cancer?
• How does zero order drug kinetics differ from 1st order?
• What is the recommended first step in the workup of an anterior neck mass?
• Which characteristic is used to measure pulmonary vital capacity?
• When should platelets be transfused for a patient with ITP undergoing splenectomy?
• What is the most common symptom following vagotomy or gastrectomy?
• What action should be taken if only 3 parathyroids are found and PTH drops appropriately?
• Which anatomical structure does the right renal artery pass posterior to?
• Which of the following is NOT a benign proliferative breast lesion associated with increased risk of cancer?
• What is the risk of pneumothorax with high levels of PEEP?
• How does a radial nerve injury typically present clinically?
• Where does the thoracic duct empty into the circulatory system?
• How many liver segments are there, and how are they categorized?
• What is a major treatment indication for focal nodular hyperplasia?
• What is a common adverse postoperative effect of colchicine?
• What is the main side effect associated with taxol?
• What is the most common method used to manage hyperthyroid patients?
• What is the most abundant amino acid present in tissue and plasma?
• What is the significance of recognizing uncompensated CHF versus MI among surgical patients?
• What type of tumor is a gastrointestinal stromal tumor (GIST)?
• What condition is most commonly associated with pyogenic liver abscess caused by portal vein seeding?
• Which of the following is the most common intraabdominal tumor in children?
• Which treatment options are primarily used for a pregnant patient with hyperthyroidism?
• Who is most likely to present with choledochal cysts?
• In the context of duodenal obstruction, what is true for children over 1 week old?
• What is the first step in the workup of a thyroid nodule after history and physical examination?
• What pancreatic enzyme is secreted in its active form?
• Which of the following signs is consistent with somatostatinoma?
• What T stage is acceptable for transanal excision of colorectal tumors?
• What is the primary treatment for anal squamous carcinoma?
• What is the most common type of organism found in diabetic foot infections?
• What is the general treatment for duodenal obstruction due to Crohn's disease after failed medical management?
• What is the anatomical relationship of the foramen of Winslow?
• What is an indication for performing angiography prior to abdominal aortic aneurysm (AAA) repair?
• A lateral boundary of a femoral hernia also includes which of the following?
• What differentiates staphylococcal scalded skin syndrome from toxic epidermal necrolysis?
• What is the primary cause of Frey's syndrome after parotidectomy?
• When considering invasive tumors, which of the following is NOT a criterion for transanal excision?
• If a recurrent laryngeal nerve injury is recognized intraoperatively, what is the preferred treatment?
• What is typically seen on a chest X-ray (CXR) in a case of Boerhaave's syndrome?
• What logistic factor is not required for low molecular weight heparin administration?
• How is the Glasgow Coma Scale (GCS) motor response scored?
• What are choledochal cysts?
• In cases of parathyroid carcinoma, what might a palpable neck mass indicate?
• What is the most common clinical manifestation of an injury to the common peroneal nerve?
• What clinical features are associated with glucagonoma?
• For which syndrome is giant liver hemangioma most notably associated in the pediatric population?
• How frequently is the bile pool recirculated?
• What is the kcal/g value for protein?
• What is the total bile pool weight in grams?
• What is the skin manifestation commonly seen in patients with Peutz-Jeghers syndrome?
• Where does GIST most commonly metastasize?
• Splenic vein thrombosis varices are most commonly associated with what condition?
• In which patient population is Lobular Carcinoma In Situ (LCIS) most commonly found?
• In which type of patients should cervical sympathectomy be avoided?
• What clinical feature would suggest the presence of parathyroid hyperplasia in a patient?
• What conditions must be met according to the Amsterdam criteria for Lynch syndrome identification?
• How does the organism enter the body in cases of amebic abscess?
• From where can the right hepatic artery originate, and what is its frequency?
• What is the hemodynamic effect of carbon dioxide pneumoperitoneum during laparoscopic surgery?
• What distinguishes HNPCC from other colorectal cancer syndromes?
• Which chemotherapeutic agent is known to cause ileus?
• How do surgical findings in parathyroid carcinoma differ from those in parathyroid adenoma?
• What unique characteristic is noted about the adrenal cortex's nerve supply?
• Which of the following are considered bad prognostic factors for thyroid cancer?
• What is the first-line treatment for Immune Thrombocytopenic Purpura (ITP)?
• What is the most common cause of sinistral portal hypertension?
• What is the primary reason for choosing incisional biopsy over excisional biopsy for larger extremity sarcomas?
• Which cancer is most likely to cause paraneoplastic hypercalcemia?
• What is another primary risk associated with HNPCC specifically in women?
• Which clinical sign is a poor prognostic indicator in the Goldman Index?
• What is the first medication that should be administered for a pheochromocytoma?
• Which treatment is typically not performed for squamous cell anal cancer?
• What is the most common congenital heart defect?
• What is the primary approach for managing asymptomatic hepatic adenomas?
• What is the primary effect of IL-6 in the acute phase response?
• Which organisms are most commonly associated with pyogenic liver abscess?
• What is the major effect of high levels of circulating glucagon?
• When a recurrent laryngeal nerve injury is recognized postoperatively, what is a common treatment method?
• When should surgery be done for hepatic adenoma?
• What is the recommended treatment for paraneoplastic hypercalcemia?
• What condition is characterized by significant fluid loss due to watery diarrhea and can lead to dehydration?
• What is the most common cardiac defect found in adults?
• Which ion is primarily secreted by the colon?
• What is the leading cause of death in children with Hirschsprung's disease?
• When is a giant hemangioma diagnosed?
• What anatomical structure serves as the lateral boundary of a femoral hernia?
• Which drug is known to be effective in treating GIST, and what is its mechanism of action?
• What is the mechanism of action of heparin in anticoagulation therapy?
• Peutz-Jeghers syndrome is characterized by what type of polyps?
• At what age do choledochal cysts typically present?
• What is the mechanism of action of omeprazole?
• What is a common complication associated with a morphine epidural?
• All types of choledochal cyst require which of the following procedures?
• What is the primary cause of hypertension in extra-adrenal pheochromocytoma?
• Which of the following is NOT a function of cholecystokinin (CCK)?
• How long after parathyroid resection should a successful PTH drop of 50% be observed?
• What is the primary mechanism of action for aminoglycosides?
• What is the management for a patient with a traumatic aortic arch injury who is hemodynamically stable?
• What is the superior laryngeal nerve a branch of?
• For GIST patients at low risk, what is the recommended treatment strategy?
• What value should cerebral perfusion pressure (CPP) be maintained above?
• In pediatric populations, what is the most common tumor found in neonates?
• What is the most commonly injured nerve during general anesthesia?
• What is the key characteristic of 1st order drug kinetics?
• What is the maximum size for focal nodular hyperplasia to be considered typical?
• For patients with thyroid cancer, what age demographic is considered a bad prognostic factor?
• Which is the most common type of choledochal cyst?
• What is a significant adverse reaction associated with the use of silvadene in burn treatment?
• How does IL-2 function in the treatment of melanoma?
• What are the first tests commonly ordered for evaluating a testicular mass?
• What is the most common pediatric malignancy?
• What is the most common clinical diagnosis in patients with Multiple Endocrine Neoplasia type 1 (MEN-1)?
• When is the use of protamine most effective?
• What are the main risks associated with choledochal cysts if not excised?
• What is the most common location for a congenital diaphragmatic hernia (CDH)?
• What key feature distinguishes GIST from leiomyoma and leiomyosarcoma?
• What is the most prevalent pediatric cancer found in the CNS?
• What is the significance of controlling hypercalcemia before addressing gastrinoma in MEN-1?
• Which GCS component is most predictive of outcome?
• What does cerebral perfusion pressure (CPP) indirectly measure?
• What condition is referred to as Frey's syndrome?
• What are the three symptoms prominently associated with Boerhaave's syndrome?
• What are the main benefits of PEEP in mechanical ventilation?
• Which of the following is an indication for surgical intervention in neonatal necrotizing enterocolitis (NEC)?
• What mutations are primarily associated with Gastrointestinal Stromal Tumors (GIST)?
• In children older than 2 years, what is the most common intra-abdominal tumor?
• What genetic mutation is commonly associated with Multiple Endocrine Neoplasia (MEN) syndromes?
• What is the relationship between basal motility and the migrating motor complex?
• How is cerebral perfusion pressure (CPP) calculated?
• What is the treatment protocol once carcinoma is suspected in a Hurthle cell neoplasm?
• What biochemical change is noted in fetal wound healing?
• Which characteristic best describes a low-risk GIST?
• Which nerve is most commonly compressed when a humerus is dislocated?
• What is the recommended treatment for anal canal cloacogenic carcinoma?
• What is the general follow-up recommendation for patients with Lobular Carcinoma In Situ (LCIS) who choose not to undergo surgical resection?
• What is the staging indication for metastasis in Hodgkin's disease?
• What is the most common visceral arterial aneurysm?
• Where does angiotensin I get converted to angiotensin II, and by what enzyme?
• What is the Respiratory Quotient (RQ) for fat metabolism?
• For types 4 and 5 choledochal cysts, what are the possible surgical options?
• Which drug acts by stimulating motilin receptors?
• What diagnostic test is often helpful in diagnosing an amebic abscess?
• In late cases of Boerhaave's syndrome, what alternative procedure is typically performed?
• What anatomical feature is noted when a replaced right hepatic artery is present?
• What causes early dumping syndrome?
• What is the initial treatment for a pregnant patient diagnosed with hyperthyroidism?
• How are short and medium-chain fatty acids absorbed?
• What is the potential risk associated with unfractionated heparin that is reduced by low molecular weight heparin?
• What surgical procedure is typically needed for a major common bile duct injury?
• What is a common complication associated with a lidocaine epidural?
• What is the most common organism found in bile?
• What anatomical structure forms the boundaries of femoral hernias?
• What is the kcal/g value for carbohydrates?
• What is not necessary when considering surgery for a large esophageal leiomyoma?
• What acid-base disturbance is typically seen with the treatment of sulfamylon (mafenide sodium)?
• What is an appropriate initial treatment strategy when steroids are ineffective in ITP?
• What confirmatory test is used in the diagnosis of Boerhaave's syndrome?
• Into what branches does the superior laryngeal nerve divide?
• When is chemotherapy or radiotherapy indicated before surgery in colon cancer based on tumor stage?