Which methods are commonly used to investigate patients with suspected colon cancer?

The most appropriate methods to investigate patients with suspected colon cancer include colonoscopy and barium enema. Colonoscopy is considered the gold standard for diagnosing colorectal cancer because it allows direct visualization of the colon and the ability to perform biopsies on suspicious lesions. This technique can also detect polyps, which are precursors to cancer, facilitating early intervention.

Barium enema, while less commonly used than colonoscopy today, is a useful radiological test that provides information about the shape and outline of the colon. It can help identify abnormalities such as strictures or filling defects and may suggest the presence of tumors. While it does not allow for biopsy, it can be an alternative in cases where colonoscopy is contraindicated.

Other methods like CT scans and MRIs are valuable in assessing the extent of disease and staging, but they are not primarily diagnostic for colon cancer itself. Instead, they are adjuncts used in the management after initial suspicion. Laparoscopy and PET scans are typically utilized in surgical planning and in assessing metastatic disease, respectively, rather than for the initial investigation of suspected cases. Thus, the combination of colonoscopy and barium enema is the standard approach for evaluating suspected colon cancer.