Surgeon Explains Rectal Cancer Surgery

Surgical oncologist explains rectal cancer surgery, use of chemotherapy and radiation, and differences from colon cancer. The surgery for rectal cancer is the most complicated of the colon and rectal cancer surgeries. This is because you have to remove the rectum from the fat and organs in the pelvis. The other organs such as uterus and vagina in women or bladder and prostate in men are very close to the rectum. The ureter tubes drain urine from the kidney to the bladder and are also close to the end of the colon and the rectum. For rectal cancer surgery, we want to remove at least 12 lymph nodes. Rectal cancer drains to lymph nodes all the way up by the sigmoid colon. The lymph nodes are intertwined with the blood vessels supplying the rectum and lower sigmoid colon. In order to remove the 12 lymph nodes we usually have to remove about one foot or more of the end of the sigmoid and rectum to at least 2 cm below the rectal cancer. In order for the remaining colon to reach into the pelvis to reconnect to the remaining rectum we have to release attachments at the splenic flexure and the left descending colon. The colon is reattached to the stump of rectum left with either a stapling device or by sewing by hand. This surgery is called a low anterior resection or abbreviated as LAR. Lastly, if the patient has had radiation before surgery this can make healing worse so we usually do not trust the re-connection of the colon and rectum not to leak as it is healing. Commonly after radiation for rectal cancer, when we remove the rectum and reconnect the colon to the remaining stump of rectum we recommend diverting stool away from the colon while it is healing – this is done with a small bowel ostomy called a loop ileostomy. This package surgery is a LAR with diverting ileostomy. The stool come out from the end of the small intestine into a bag. After several weeks or months a surgery can be done to reconnect the small intestine and stool will go back through the colon and out from the now-healed reconnected colon and rectum. For large rectal cancer or rectal cancer that is very close to the anus – sometimes a surgeon cannot reconnect the colon to any rectum that is left. If this is the case, then we may have to remove the entire rectum along with the anus and sew the space where the anus was shut completely. This obviously requires a colostomy which is brought up to the skin from the end of the remaining colon and this is a permanent colostomy for the rest of your life. This surgery is called an abdominoperineal resection abbreviated as APR. Adenocarcinoma of the colon is usually removed with surgery then chemotherapy is given if needed. Radiation is rarely used in colon cancer. One major difference between colon and rectal cancer is that rectal cancer frequently uses radiation. The wall of the rectum has layers and the middle layer is muscle. For early rectal cancer that has not invaded through the muscle layer in the wall located in the rectum you may just have surgery and not get chemotherapy or radiation. But if the cancer is growing deep into the wall of the rectum through this muscle layer or looks like it is already in lymph nodes on x-rays – then we will commonly use radiation before doing surgery. Radiation helps shrink the tumor making surgery easier and can decrease regrowth of the tumor. If you are getting radiation for rectal cancer you will frequently be given a very light version of chemotherapy that makes the radiation work better. True chemotherapy with multiple types of chemo is not given at the same time as radiation as this can cause too many side effects. Radiation with “lite chemo” lasts 5-6 weeks. Radiation is given with a big machine and the invisible beams will travel through the area of the rectal cancer. This is given by a radiation oncologist doctor. After finishing radiation we wait 6-10 weeks to allow the tissue to recover before doing surgery. After radiation we typically do surgery next then chemotherapy - if needed - comes last. So quick recap – early rectal cancer not growing through the muscle of the wall of the rectum gets surgery and no other treatment. Deeper rectal cancer growing through muscle layer or into lymph nodes gets radiation with “lite chemo”, then surgery, then chemotherapy after.
Sometimes if a cancer is very small and early and has not grown into the muscle of the wall of the rectum and is in the lower third of the rectum, we may be able to remove it from the anal opening just by taking out a part of the wall of the rectum and stitching it shut. This is called a trans-anal excision. This is only for very small early rectal cancer and is sparingly used since we cannot check lymph nodes with this technique.

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