A 65-year-old man is referred to a gastroenterology clinic by his primary care provider after he develops symptoms suspicious for colorectal cancer. The patient has a history of obesity, diabetes mellitus, and chronic obstructive pulmonary disease. He often eats steaks and hamburgers but avoids vegetables as "they have no flavor." The patient has smoked a pack of cigarettes daily for the past 40 years and occasionally consumes alcohol. He undergoes a colonoscopy and is found to have a mass lesion in the ascending colon. The mass is biopsied, and the histopathologic findings are consistent with colon adenocarcinoma. This patient most likely initially presented with which of the following clinical symptoms?

Question

A 65-year-old man is referred to a gastroenterology clinic by his primary care provider after he develops symptoms suspicious for colorectal cancer.  The patient has a history of obesity, diabetes mellitus, and chronic obstructive pulmonary disease.  He often eats steaks and hamburgers but avoids vegetables as "they have no flavor."  The patient has smoked a pack of cigarettes daily for the past 40 years and occasionally consumes alcohol.  He undergoes a colonoscopy and is found to have a mass lesion in the ascending colon.  The mass is biopsied, and the histopathologic findings are consistent with colon adenocarcinoma.  This patient most likely initially presented with which of the following clinical symptoms?

Quizplus · Accepted Answer

The location of colon adenocarcinoma can influence its clinical manifestations. Right-sided colon cancers usually grow as exophytic masses. Patients generally do not develop intestinal obstruction because the ascending colon has a larger caliber lumen than the descending colon and stool in the proximal colon is more liquid. Right-sided colon cancers typically present with features of iron deficiency anemia (eg, fatigue, pallor) due to occult blood loss. Nonspecific symptoms such as anorexia, malaise, and unintentional weight loss may also occur. Environmental and lifestyle factors that may have increased this patient's risk of colon cancer include obesity, cigarette smoking, consumption of red/processed meat, and low dietary intake of vegetables. (Choice A) Left-sided colon cancers tend to infiltrate the intestinal wall and encircle the lumen, causing a change in bowel habits (eg, constipation) and symptoms of intestinal obstruction (eg, abdominal pain, distension, nausea/vomiting). (Choice B) Constipation that alternates with diarrhea is characteristic of irritable bowel syndrome. (Choice C) Recurrent grossly bloody stool associated with abdominal discomfort and low-grade fever is characteristic of ulcerative colitis, which is a risk factor for colon cancer. Rectosigmoid cancer often causes hematochezia, but fever is uncommon. (Choice D) Tenesmus (ineffectual/painful straining on defecation) and small-caliber stool are characteristic of rectal adenocarcinoma. Educational objective: Right-sided colon cancers usually grow as exophytic masses and present with occult bleeding and symptoms of iron deficiency anemia. Left-sided colon cancers tend to infiltrate the intestinal wall and encircle the lumen, causing constipation and symptoms of intestinal obstruction. Rectosigmoid involvement often causes hematochezia. __________ References: Left and right sided large bowel cancer. (http://www.ncbi.nlm.nih.gov/pubmed/11964327) Correlation of clinical data, anatomical site and disease stage in colorectal cancer. (http://www.ncbi.nlm.nih.gov/pubmed/18817021) How does colorectal cancer present? Symptoms, duration, and clues to location. (http://www.ncbi.nlm.nih.gov/pubmed/10520866)

A 65-Year-Old Man Is Referred to a Gastroenterology Clinic by His