A 54-year-old man comes to the office due to intermittent episodes of blood in the stool over the past several weeks. The blood is mixed in the stool, and he has also noticed bright red blood on the toilet paper. The patient reports no prior medical conditions but has not seen a physician in many years. Family history includes colon cancer in his paternal uncle. Vital signs are within normal limits. Physical examination shows a nondistended, soft, and nontender abdomen with no hepatosplenomegaly. A palpable mass is present on digital rectal examination. Flexible sigmoidoscopy confirms a fungating mass in the upper rectum; biopsy is consistent with adenocarcinoma. Staging CT scans reveal no lung, liver, or bony metastases. Which of the following is most appropriate prior to surgical treatment of this patient's condition?

Question

A 54-year-old man comes to the office due to intermittent episodes of blood in the stool over the past several weeks.  The blood is mixed in the stool, and he has also noticed bright red blood on the toilet paper.  The patient reports no prior medical conditions but has not seen a physician in many years.  Family history includes colon cancer in his paternal uncle.  Vital signs are within normal limits.  Physical examination shows a nondistended, soft, and nontender abdomen with no hepatosplenomegaly.  A palpable mass is present on digital rectal examination.  Flexible sigmoidoscopy confirms a fungating mass in the upper rectum; biopsy is consistent with adenocarcinoma.  Staging CT scans reveal no lung, liver, or bony metastases.  Which of the following is most appropriate prior to surgical treatment of this patient's condition?

Quizplus · Accepted Answer

11ec25c8_d8e8_92b1_bc81_a769d257cb9d_MD0003_00 This patient has adenocarcinoma of the rectum, presenting with rectal bleeding and confirmed on flexible sigmoidoscopy. Sigmoidoscopy is generally well tolerated by patients and is an effective tool for evaluating lesions in the distal colon. It can also be considered for colorectal cancer screening in low-risk individuals and has been shown to reduce colorectal cancer mortality. The procedure can be performed in an office setting by gastroenterologists and trained primary care or advanced care providers. However, abnormal results on sigmoidoscopy often require follow-up colonoscopy. Sigmoidoscopy does not visualize beyond the rectosigmoid colon. Patients with left-sided adenomas or adenocarcinomas have increased risk for synchronous neoplasia in the right colon and therefore require visualization of the entire colon with colonoscopy (Choice D). In addition, the staging evaluation should include CT scans of the chest, abdomen, and pelvis to identify distant metastasis. Carcinoembryonic antigen (CEA) levels are also helpful for prognostication, although they exhibit low sensitivity and specificity for metastasis. (Choice A) Familial adenomatous polyposis (FAP) is caused by mutations in the Adenomatous Polyposis Coli (APC) gene and confers a very high risk of colorectal adenocarcinoma. However, affected individuals typically have numerous colon adenomas, not a solitary mass. Also, a more extensive family history would be expected because FAP is autosomal dominant with nearly 100% penetrance. (Choice C) Patients with Lynch syndrome (hereditary nonpolyposis colorectal cancer) are at increased risk for gastric adenocarcinoma and warrant periodic upper endoscopy to detect early adenomatous polyps. However, patients typically have an extensive family history of colon, endometrial, ovarian, and stomach cancers across multiple generations. (Choice E) Lymphatic drainage from areas distal to the anal dentate line involves inguinal lymph nodes. To rule out lymphatic metastasis in anal cancer, a sentinel inguinal lymph node biopsy is often obtained at the time of tumor resection. This is unnecessary for rectal tumors proximal to the anal dentate line because lymphatic drainage from this region goes to the inferior mesenteric and internal iliac, but not the inguinal, lymph nodes. Educational objective: Sigmoidoscopy is an effective tool for evaluating lesions in the distal colon but does not visualize the right colon. Patients with left-sided adenomas or adenocarcinomas detected on sigmoidoscopy have increased risk for synchronous neoplasia on the right side and require visualization of the entire colon with colonoscopy. References: Colonoscopy surveillance after colorectal cancer resection: recommendations of the US Multi-Society Task Force on colorectal cancer. (http://www.ncbi.nlm.nih.gov/pubmed/26871541)

A 54-Year-Old Man Comes to the Office Due to Intermittent