Colon and rectal cancer is the third most frequent cancer in the world in men and the second in women, with approximately 1.4 million cases and 693,900 deaths occurring in 2012.
The main risk factors are male sex, advanced age, certain lifestyles (alcohol, tobacco, overweight), certain diets (red meat, processed meats, diets poor in fiber…) and hereditary factors.
Most of these tumors originate from a benign lesion called a polyp. The detection and removal of polyps when they have not yet developed into cancer means avoiding the appearance of cancer as such, and therefore reducing mortality from this tumor.
More specifically, cancers located in the rectum account for almost half of all colorectal cancers, but their treatment is more complex than those located in the rest of the colon. The very particular anatomy of the rectum in the narrow area of the pelvis makes surgical access relatively difficult. In addition, it is important to dissect exactly the right anatomical planes to completely eradicate the cancerous disease.
What symptoms and signs can detect rectal cancer?
The most common symptom of rectal cancer is bleeding. Unfortunately, this bleeding is most often attributed to hemorrhoid problems, and correct diagnosis is delayed until the cancer has reached a more advanced stage. It is for this reason that at the slightest perception of bleeding in the stool it is necessary to go to a specialist in Coloproctology.
Rectal cancer produces a series of symptoms that may vary depending on its location within the large intestine. These symptoms are the following:
- Blood in the stool: this is one of the most frequent symptoms of colon cancer. It may be red blood, more frequent in tumors of the sigmoid and descending colon, or black blood, which mixes with the stool giving rise to black stools called melenas. Melenas appear more frequently when the tumor is located in the ascending colon. When the disease is not detected, anemia usually appears, which can cause tiredness, palpitations, dizziness…
- Change in the rhythm of bowel movements: diarrhea or constipation appear in people with a previously normal bowel rhythm. Diarrhea and constipation alternate normally.
- Narrower stools: this usually occurs because the tumor is narrowing the intestine and does not allow normal passage of stool.
- Tenesmus or sensation of incomplete evacuation: it usually appears in tumors located in the most distal part of the colon.
- Abdominal pain: this is usually a frequent symptom. When the tumor partially closes the caliber of the intestinal tube, a picture of colicky abdominal pain is produced. When the closure is complete it is called intestinal obstruction, which is a serious clinical situation that requires urgent medical assistance. There is prolonged constipation, nausea, vomiting, abdominal pain and general malaise.
- Extreme fatigue or unexplained weight loss: these are general and non-specific symptoms that occur frequently in certain diseases, including advanced colon tumors.
Can rectal cancer be prevented and is it hereditary?
Depending on the presence of risk factors, three groups are distinguished:
- Low risk: group formed by people under 50 years of age with no family history of colorectal cancer or polyps. In this context, it is unlikely to develop a cancer of this type, so it is not necessary to take preventive measures.
- Medium risk: people over 50 years of age, with no history of colorectal cancer.
- High risk: people who have a family history of colorectal cancer, who have already had cancer or who belong to a family with hereditary cancer. In these cases, the chances of developing colorectal cancer are higher.
How is it detected early?
Colorectal cancer can often be prevented by regular screening tests that can find polyps before they become cancerous. This is the target of early detection programs.
Colorectal cancer screening is the detection of this tumor or pre-malignant polyps when it has not yet presented symptoms. Screening allows, on the one hand, the detection of polyps before they degenerate into cancer. On the other hand, it allows the detection of cancer at an early stage when treatment is less aggressive and more successful.
What is the best screening test for rectal cancer?
- In patients without symptoms
It has been shown that colorectal cancer screening by any of the currently available strategies – fecal occult blood detection, sigmoidoscopy and colonoscopy – is cost-effective compared to no screening at all, which means that population screening programs save money for healthcare systems, given the high cost of cancer treatments.
As to which is the best test, there is no comparison between them. In the medium-risk population, there is research comparing colonoscopy performed every ten years with fecal occult blood detection by immunological method every one or two years.
- In patients with symptoms
If the patient presents symptoms, usually through rectorrhagia, the most effective test for diagnosis is colonoscopy.
How is rectal cancer treated?
Once the tumor has been identified by means of the relevant tests (colonoscopy, biopsy, endoscopic ultrasound, MRI and thoracoanal CT), we will know how to treat it.
- Local excision: this is an excellent operation for small cancers located near the anus and which have not penetrated the muscular layer. However, this technique does not allow removal of the lymph nodes of the rectal mesentery. This operation is indicated for tumors smaller than 4 centimeters, mobile and in early stages.
- Low Anterior Resection with colorectal anastomosis: allows the removal of the bowel containing the cancer and the mesorectum where the lymphatic ducts into which the tumor drains are lodged. Intestinal continuity is restored by joining the colon to the rectum.
- Abdominoperineal amputation: this occurs when it is necessary to remove the anal sphincters because they are infiltrated by the tumor, which makes it necessary to remove the anus, so that the patient has a permanent colostomy.
Depending on the preoperative staging, radiotherapy or preoperative chemotherapy will be indicated.
What is the postoperative course of rectal cancer?
The postoperative evolution will depend on the technique used. Minimally invasive techniques, such as laparoscopic surgery or transanal endoscopic surgery, allow the evolution to be more comfortable for the patient, while requiring a shorter hospital stay.