Colorectal cancer

Colorectal cancer is cancer of the large intestine including the colon and rectum. According the most recent National Cancer Registry (NCR) data from 2019, there were 1 952 new cases of colorectal cancer diagnosed in females accounting for 4,46% of cancer cases in females.

Diagnosis

Any cancer needs a histological diagnosis. Although the primary tumour may be palpable with a rectal examination, seen on CT scan or visible on colonoscopy, a biopsy is needed to confirm the diagnosis. The excised tissue is sent to a laboratory where the histopathologist will comment on the type of cancer. The staging and molecular profile will be included in the analysis and is important for the planning of the correct therapy and order of therapy for each individual patient.

Along with the diagnosis, the staging of the cancer is important and a work-up, such as a CT scan (chest, abdomen, and pelvis), PET-CT or sonar of the liver and chest X-ray, will be performed to decide on the treatment and will help with prognostic evaluation.

Treatment

There are different modalities of treatment for colorectal cancer and the treatment needs to be individualised to the patient and the type of cancer. The treatment modalities include surgery, radiation, chemotherapy, targeted therapy and in some instances immunotherapy.

It’s important to differentiate and understand colorectal cancer to decide on the right therapy. The first 13cm from the anal verge is considered the rectum and it’s a pelvic organ. The treatment is slightly different and includes radiation. 

Rectal cancer will need total neoadjuvant therapy which includes chemotherapy, followed by combined chemo-radiation (low-dose chemotherapy, tablets or intravenous therapy at the same time as daily radiation), short course or conventional course of radiotherapy and then followed by surgery within a specific period to ensure optimal response and healing after surgery. 

If the cancer is too close to the anal verge, an abdominoperineal resection will be performed with a construction of a permanent colostomy (the colon is shortened to remove the cancerous part and the cut end diverted to an opening in the abdominal wall). 

Occasionally, the tumour may be further from the anal verge and a re-anastomosis can be performed later when the patient has recovered and treatment has been completed.

If a rectal tumour is classified as microsatellite instability-high, recent studies have shown that immunotherapy may be the only therapy needed. This needs to be discussed with the oncologist as this therapy hasn’t been widely accepted onto protocols and is costly.

After removal and staging, chemotherapy for colon cancer (beyond 13cm from the anal verge) as preventative therapy is recommended for Stages 2b and beyond. No radiation is indicated. 

Left side vs right side

The colon is traditionally divided into three parts: the ascending colon (starts at the caecum on the right side of the abdomen), transverse colon, and descending colon (ending in the sigmoid and then the rectum on the left side of the abdomen).

There is a distinction between left- and right-sided colon cancer and the division between the left and right side of the colon lies in the transverse colon. The left-sided colon is from the last third of the transverse colon up to the distal rectum and the right-sided colon includes the ascending colon and the first two thirds of the transverse colon. Left-sided cancer carries a better prognosis and treatment choices are different between the two sides.

For neo-adjuvant or adjuvant therapy for Stage 4 disease (rectal and colon), chemotherapy may be combined with EGFR blockers, such as panitumumab or cetuximab for left-sided colon cancer. 

For KRAS mutations and right-sided tumours, bevacizumab in combination with chemotherapy will deliver the best results.

Survivorship

The term cancer survivor has been used variably in the literature; most commonly, a cancer survivor refers to any person who has been diagnosed with cancer for the balance of their life. It’s like a membership to a club, but you can’t renounce the membership. Therefore, survivorship begins at the time of diagnosis and includes the periods of initial treatment with intent to cure, cancer-free survival, chronic or intermittent disease, and palliative care.

Patients often have physical adaptations to make because of treatment, such as living with scarring of a midline incision and/or a permanent colostomy bag. There may be feelings of embarrassment as there is no control when a bowel action may take place despite the fact that the colostomy bag is sealed.Having a permanent colostomy bag will affect body image and sexuality. 

Neuropathic pain syndromes after surgery or even symptoms of irritable bowel syndrome may permanently alter diet and quality of life. There may be long-term side effects from chemotherapy, such as peripheral neuropathy and radiation colitis if the tumour was in the rectum.

There is psychosocial stress, and the fear of recurrence often leads to re-evaluation of relationships and the patient’s role in society. Not looking ill and not losing hair with treatment of this disease may cause others to expect the patient to return to normal more often than patients who lose their hair with other types of cancer.

A clear plan needs to be set out for the patient in terms of follow-up and investigations to be done. Support groups, including friends made during treatment, may help with returning to society and to find a new normal. Always remember that your oncology team understands your disease, complications and fears and will always be there to support you.