American Mayo Clinic experts talk about the treatment of rectal cancer

Rectal cancer is cancer that occurs in the last few inches of the colon, an area called the rectum. If detected early, the long-term survival rate is about 85% to 90%, but if the cancer spreads to the lymph nodes, survival rates drop sharply. Most rectal cancers start with small non-cancerous growths called polyps, which can be removed before they become cancerous — making timely colonoscopy screening critically important. Prevention guidelines generally recommend colonoscopy screening beginning at age 50, or earlier for those with risk factors such as a family history of colorectal cancer.

Many patients with rectal cancer have no signs or symptoms in the early stages. Later-stage symptoms may include rectal bleeding (often bright red and frequently mistaken for hemorrhoids), changes in bowel habits, abdominal discomfort, rectal pain, and a persistent feeling of needing to use the bathroom. Patients should not assume rectal bleeding is due to hemorrhoids without a proper medical examination to rule out polyps or cancer. Diagnosis is confirmed through a combination of colonoscopy, CT scan or X-ray, and additional tests such as endoscopic ultrasonography or MRI to determine whether the cancer has penetrated beyond the rectum or involved nearby lymph nodes.

Rectal cancer is staged based on how far the tumor has progressed. Stage I cancer has not grown through the rectal wall and has not spread to lymph nodes. Stage II involves a tumor that has invaded or slightly passed through the rectal wall without lymph node involvement. Stage III means the cancer has spread to nearby lymph nodes, and Stage IV indicates the cancer has spread to other areas of the body.

Surgery is the most common treatment across all stages and involves removing the cancerous portion of the rectum along with margins of healthy tissue and nearby lymph nodes. When possible, the surgeon reconnects the remaining healthy portions of the rectum and colon. If reconnection is not possible, a permanent colostomy — an opening through the abdominal wall — may be required. For locally advanced rectal cancer at Stage II or III, chemotherapy and radiation therapy are typically used before surgery to shrink the tumor and improve the likelihood of complete removal, followed by additional chemotherapy after surgery. Patients are strongly advised to consult their doctor promptly when early symptoms appear, particularly rectal bleeding, changes in stool size or characteristics, or persistent rectal discomfort.