Rectal cancer

Condition symptoms

The main function of the rectum is the formation and excretion of fecal material. Therefore, defecation disorders are the first symptoms of the disease. It may be constipation or diarrhea, at first the symptoms are transient, but with the growth of the neoplasm, the feces of normal consistency become very rare.

Often there are false urges, when with a small amount of feces there is an overwhelming desire to evacuate one’s bowels, which is called «rectal spittle». Very often, after defecation there is no feeling of complete emptying of the intestine, if the cancer is located near the anus, then during the bowel movement there is a disturbing pain.

The second sign is appearance of blood in the feces, at first only by streaks, then clots are released, sometimes with an admixture of mucus. The presence of mucus without blood is not considered a sign of rectal cancer. With chronic blood loss, blood test is made for anemia, a lack of red blood cells and hemoglobin.

Intense chronic pain occurs during invasion of the entire intestine wall and involvement of the pelvic nerve plexus. If the cancer spreads to the urinary bladder, then symptoms of a cystitis resistant to standard treatment appear. When cancer invades vaginal tissues, there is pain during intercourse.

Rectal cancer progresses aggressively even with a favorable histological structure, a well differentiated adenocarcinoma. The process is prone to relapse and rapid metastasic spreading, most often to the liver and lungs. The high degree of malignancy coincides with the sensitivity to irradiation and chemotherapy, but cancer cells quickly develop resistance, that is, a self-defense strategy. The leading treatment method is surgery, which is preceded by radiation therapy (RT), sometimes together with several cycles of chemotherapy (CT), and prophylactic medication is excluded only at stage I.

The main set of therapeutic measures can be supplemented by innovative local methods of destruction by various physical factors and targeted drugs. But with an advanced process, even the most advanced approach does not promise a complete cure, that’s why it is so important to identify the malignant process at the very beginning, preferably at the stage of a villous polyp.

Therapy tactics

The neoplasm is detected by digital examination, and an endoscopic examination called sigmoidoscopy is always performed, during which a piece of the tumor is taken for microscopy. A colonoscopy is always performed, because occurrence in the large intestine of several cancer nodules at once is rare but possible.

Before starting treatment, MRI of the lesser pelvis is performed to establish the size of the formation and involvement of the neighboring organs and tissue of the lesser pelvis.

Radical treatment of rectal cancer necessarily includes surgery. At stage 1, endoscopic surgery or the most sparing and organ-preserving resection is performed.

The scope of intervention at stage 2 depends on the localization of the tumor in the organ and its true size, a poorly differentiated adenocarcinoma requires chemotherapy. At stage 3, preventive chemotherapy is required after surgery, supplemented with irradiation.

What operations are performed for rectal cancer?

• In case of an early adenocarcinoma, an organ-preserving endoscopic transanal resection is sufficient, when the entire malignant tumor is microsurgically removed with a small area of the intestinal wall. The cancerous lesion should be very small, not exceeding 3 cm, and should occupy no more than one third of the intestine circumference, not penetrating beyond the mucous membrane and having no signs of cell aggressiveness. If, with minimal surgery, subsequent histological examination reveals unfavorable prognostic signs, a repeated operation of a larger scope is possible.
• A rather extensive part of the organ is excised during mesorectuctomy, depending on the location of the cancer conglomerate. This resection option may be partial or total, without a temporary output of the end portion on the abdominal wall, or with an ileostomy. In the lower third of the intestine closer to the anus, a practically similar intervention is called abdominal-anal or intersphincter resection. If it is necessary to relocate the anus to the abdomen, the patency of the intestinal tube is fully restored after some time, as a rule, after completion of preventive chemotherapy.
• Crippling abdominal-perineal extirpation is also still performed, when the cancerous lesion does not allow for another option, and large arrays of tissue are removed in the process of pelvic evisceration for a relapse after radical treatment. In both cases, the intestine is exteriorized on the abdominal wall, creating thus an artificial anus, and a postoperative scar remains in place of the anatomical anus.

Currently, there is a tendency to operate each patient. If the tumor is initially inoperable, then at the first stage chemoradiation treatment is performed, after which the possibility of delayed surgical treatment is discussed. As a rule, the probability of a surgical intervention is questionable in case of multiple and non-removable metastases, but an oncologist advises the patient in each case, at all stages of treatment.

What is the treatment for stages 1, 2 and 3 of rectal adenocarcinoma?

With early stage 1 cancer, endoscopic resection is applied, and most patients can be cured without any additional exposure, so no radiation or chemotherapy is performed.

With a larger lesion of the intestinal wall depth by the malignant process, but without seeding of cancer cells into peripheral lymph nodes (stage 2), a part of the organ is also resected, but widely this time, applying mesorectimectomy. If the relapse probability is low, the treatment is considered completed. In the presence of cellular signs of an unfavorable prognosis, preventive chemotherapy is perfromed for six months.

At stage 3 of adenocarcinoma, irradiation is performed before surgery. With 5-day large-fraction radiotherapy, resection is performed as early as 3 days after the last session, but in very elderly patients or with associated chronic diseases, the intervention can be postponed for 4–6 weeks until full recovery.

With a long-term 10–12 week irradiation against the background of weekly administration of drugs (to improve the result), surgery is performed 6–8 weeks after completion of radiation therapy sessions. When radiation therapy is not performed before the operation, it is prescribed after the intervention to prevent early cancer relapse. Preventive chemotherapy is mandatory for all patients for half a year.

What tactics is adopted for stage 4 cancer?

With an initially inoperable stage 3 process, a large neoplasm impacted into the surrounding tissue, long-term radiation therapy is performed at the first stage against the background of medication. If the tumor has shrunk and the intestine can be technically removed, the operation is planned in 10–12 weeks, with prior performance of chemotherapy. If it is not possible to remove an adenocarcinoma after prolonged irradiation, 4–6 additional courses of chemotherapy are performed, after which the possibility of removal is discussed again. After surgery, the chemotherapeutic exposure is brought to a total semi-annual duration.

Stage 4 is not a contraindication to surgery if it is possible to remove hepatic and pulmonary metastases, but at the first stage, up to 6 chemotherapy cycles are performed. After chemotherapy, surgery is performed with simultaneous excision of the rectal tumor and resection of metastases, or all tumors are removed in several sessions, including such innovative methods as laser or radio frequency ablation (RFA), and cryodestruction.

With non-removable multiple metastatic foci, palliative intestine resection is not excluded, again against the background of systemic multi-cycle drug treatment. There are many options for combining methods, but surgery is always a priority.

What chemotherapy is applied for rectal adenocarcinoma?

• For adjuvant or prophylactic chemotherapy, FOLFOX and XELOX schemes are prescribed.
• At stages 2 and 3, only tablet forms of drugs are used. The duration of preventive therapy is 6 months.
• No optimal standard options have yet been found for therapy of generalized metastatic process. There is no single strategy, different options are possible: to perform a semi-annual cycled chemotherapy until the cancer process stabilizes and stop without resorting to chemotherapy until signs of progression appear; after 3–4 months of combined chemotherapy in any of the regimens, to continue treatment to maintain the achieved result; the third approach is to administer treatment as long as there is no severe toxicity or the patient has enough strength.

Targeted adenocarcinoma therapy

A targeted drug, unlike the one intended for chemotherapy, interrupts a certain biochemical process disrupting the reproduction of cancer cells. Cytostatic chemotherapy is enhanced by a targeted drug from the group of monoclonal antibodies, since a targeted drug alone has not shown efficacy.

With colonic cancer, a mutation of the CRAS gene is necessarily detected in the tumor; if it is not present, the use of a monoclonal antibody against the specific vascular factor EGFR is useful.

Clinical studies have demonstrated the benefit of using a progressive blocker of the cell enzyme protein kinase for advanced rectal cancer.

All antitumor drugs affect both cancer and normal cells, which is manifested by side reactions, the spectrum of which is diverse, and the intensity is individual.

This text is based on the materials of NCCN (National Cancer Comprehensive Network).

Treatment of rectal cancer is a very difficult task, where a positive result depends on the biological characteristics of the cancer cells, but the clinic’s possibilities are also important, while the national clinical recommendations make a special emphasis, because the optimal treatment of each clinical case is available only to highly qualified experts, like the ones who work in our clinic.