How is rectal cancer treatment planned?

Treatment for rectal cancer does not always start with surgery. First, tests establish how far the tumour has grown into the bowel wall and whether it has spread to surrounding tissues or other organs. The surgeon, oncologist and other specialists then review the findings together to decide the order of treatment.

For some early tumours, surgery is the first step. In more advanced disease, drug treatment and radiotherapy may be needed before surgery. This sequence is not an unnecessary delay to the operation: the aim is to shrink the tumour, make complete removal easier and reduce the chance of the disease returning. This is why two people with the same diagnosis may have different treatment plans.

Tests that establish the stage

A colonoscopy examines the inside of the colon and rectum using a thin instrument with a camera. A small tissue sample taken from the tumour during the examination, called a biopsy, is assessed in the laboratory. Examining this tissue confirms the cancer diagnosis. However, a biopsy alone does not show how far the disease has spread.

Magnetic resonance imaging, or MRI, of the pelvis provides a detailed view of the area around the rectum. It assesses whether the tumour extends beyond the bowel wall, the appearance of nearby lymph nodes and how close the tumour is to the boundaries of the tissue to be removed during surgery. Lymph nodes are small structures in the immune system; cancer cells can spread to them. A lymph node that looks suspicious on MRI does not automatically mean cancer.

Computed tomography, or CT, of the chest and abdomen helps check distant organs, particularly the lungs and liver. Blood tests also provide information about general health. The doctor establishes the stage by bringing all these findings together: tumour depth, lymph nodes and distant spread are considered together.

Additional tests called MMR or MSI testing may also be requested on the tumour tissue. These look for changes in the system that repairs genetic errors in cells. Certain results may make immunotherapy, which strengthens the immune system's activity against the tumour, an option; this does not apply to every patient.

How is the treatment decision made?

The test results are usually discussed at a multidisciplinary team meeting. This brings together the surgeon, the oncologist who plans drug treatment, the radiotherapy specialist, the radiologist who interprets the images and the pathologist who assesses the tissue. Each sees a different aspect of the same disease.

The team considers more than tumour size. Heart and lung conditions, nutrition, independence in daily activities, previous treatments and the patient's preferences also matter. The aim, stages and possible side effects of the proposed plan should be discussed with you individually.

Bringing your biopsy report, MRI and CT images and a list of your medications to the appointment makes assessment easier. The written scan report alone is sometimes not enough: the team may also need to review the images themselves. This assessment explains the answer to “Why not operate first?”

The purpose of treatment before surgery

Chemoradiotherapy combines radiotherapy with a cancer drug that increases its effect. The radiation is directed at a specific area, while the choice of drug and treatment duration are determined by the plan. Treatment may help shrink the tumour, but the degree of response cannot be predicted precisely.

Total neoadjuvant therapy, or TNT, is an approach in which the planned chemotherapy and radiotherapy are completed before surgery. Chemotherapy is drug treatment for cancer. The aim is to treat both the tumour in the pelvis and any possible spread that is not visible on scans. This approach is discussed particularly for locally advanced disease with a high risk of recurrence.

Not everyone receives the same regimen. In selected lower-risk cases, the use of radiotherapy may be planned differently; some early tumours do not need this treatment before surgery. Blood test results, nutrition and side effects are monitored during treatment. If diarrhoea, fatigue or difficulty eating develops, you do not need to keep it to yourself until the next appointment.

Is surgery still needed if the tumour is no longer visible?

After treatment, the tumour is reassessed with repeat MRI, a finger examination of the rectum and a camera examination inside the bowel. If none shows signs of remaining tumour, this is called a complete clinical response. It does not prove that not a single cancer cell remains in the tissue.

For selected patients, a “watch and wait” approach involving close monitoring may be discussed. Surgery is not performed immediately; instead, a predefined programme of frequent examinations is followed. This decision is made with an experienced team and requires the ability to attend regular follow-up appointments.

The tumour may grow back. If this is detected, surgery is considered again. Feeling well and no longer bleeding do not replace the monitoring programme; deciding against surgery on the basis of symptoms alone is not a watch-and-wait approach.

Surgery and the subsequent tissue results

One of the main surgical principles for mid- and low rectal tumours is total mesorectal excision, or TME. The mesorectum is the fatty tissue around the rectum that contains blood vessels and lymph nodes. During surgery, the part of the bowel containing the tumour is removed together with this tissue along the appropriate anatomical boundaries.

Surgery performed through small abdominal incisions using a camera is called laparoscopic surgery. Laparoscopic Surgery for Rectal Cancer, used in suitable cases, follows the same cancer surgery principles. Tissue dissection can be seen in the video Laparoscopic TME for rectal cancer; this is surgical footage intended for adults.

The laboratory report on the removed tissue shows whether any tumour remains, the findings in the lymph nodes and the cut margins. Further treatment and follow-up are based on these results, as well as the treatment already given.

If you develop severe abdominal pain, abdominal swelling, inability to pass wind or stool, vomiting or heavy bleeding while waiting for scheduled examinations, urgent medical care is needed. These may be signs of bowel obstruction or another complication.