Rectal cancer is the name given to carcinoma, or cancer, of the rectum.
The rectum is the last part of the bowel. It is found in the pelvis. It stores faeces and flatus (wind) before it passes out of the anus.
Carcinoma or cancer is a malignant growth of the surface lining, or epithelium, of a body or structure.
Rectal cancer therefore is a malignant growth that starts in the lining of the rectum. Colorectal cancer, meaning cancer of the colon or rectum, is one of the most common malignancies or cancers in humans. The commonest site of colorectal cancer is at the junction of the sigmoid colon and rectum – a site called the rectosigmoid junction. This is found right at the point where the pelvis meets the abdomen, at the back of the pelvis on a bone called the sacrum.
Rectal cancer is often first suspected if a patient has symptoms of alteration of their bowel habit, or if they start to notice blood mixed in with their faeces.
The causes of rectal cancer are thought to be a combination of genetics and other environmental factors. Obviously one cannot change one’s genetics. Environmental factors can often be changed and so much research is performed into trying to identify which ones are highly specific for rectal cancer.
It appears that a high diet of red meat and also slow bowels are associated with rectal cancer. The reason that slow bowels are associated with rectal cancer is this allows the toxic substances to stay in contact with the rectal lining for longer than normal. Therefore anything that speeds up the bowels, such as roughage (fibre) seems to be protective against rectal cancer.
Most rectal cancers seem to start off as polyps which are warty like projections into the rectum from the surface.
Rectal cancer usually means an operation to remove it. Survival after rectal cancer varies depending on how deep the cancer has spread into the wall of the rectum.
The Dukes classification is used to classify rectal cancer into A,B and C. Dukes was a pathologist and so was able to examine rectal specimens after removal. Dukes A means the cancer is confined to just the lining. Dukes B means the cancer is spreading into the muscle and Dukes C means it has spread beyond the muscle into the local lymph nodes. Many people use a Dukes D classification meaning the cancer has spread further into distant lymph nodes or liver. Although this is a useful classification to work out survival, it was not described by Dukes as he only ever examined specimens removed at surgery rather than the whole patient. This is a common misconception.
Much research is being performed into new ways of treating rectal cancer including minimally invasive or laparoscopic surgery and also other modalities to work with surgery or occasionally instead of – such as chemotherapy and radiotherapy.