Rectal Cancer

Initial Assessment

Tissue diagnosis is important so a biopsy needs to be done. After that a staging scan should be done to check the extent of tumour, spread to nearby lymph nodes or to other organs.

STAGING SCAN

CXR + CT Abdomen & Pelvis

CT Chest, Abdomen & Pelvis

18FDG PET-CT

MRI Pelvis

For recurrent cancers, staging scans will need to be repeated to assess the extent of cancer.

TREATMENT

STAGE I

Surgery will be the most appropriate treatment if the patient is medically fit for surgery.

The outcome is excellent and no further therapy is required after surgery.

STAGE II

Surgery will be the most appropriate treatment if the patient is medically fit for surgery.

Occasionally a short course of 5 sessions of radiotherapy may be recommended the week prior to surgery.

After surgery, it is important to see an oncologist to discuss the need for chemotherapy for deeper or larger tumours and/or invasion of cancer cells into the blood or lymphatic

vessels in and around the tumour. The purpose of such chemotherapy is to mop up small amount of cancer cells that may still be in the body.

Standard chemotherapy after surgery will include a fluoropyridimine drug eg 5 Fluorouracil or Capecitabine and will last up to 6 months.

STAGE III

Surgery will be the most appropriate treatment if the patient is medically fit for surgery.

A significant majority of patients will require a short course of 5 sessions of radiotherapy the week prior to surgery. If the cancer is bigger and deeper and difficult to operate on immediately, a longer course of 5 weeks of concurrent radiotherapy and fluoropyrimidine chemotherapy may be necessary to shrink the cancer. The complexity of surgery increases with the extent of the tumour and surrounding nodes, as well as how low the cancer is in relation to the anus.

After surgery, a vast majority of patients will benefit from chemotherapy if they are fit enough to receive this treatment. The purpose of such chemotherapy is to mop up small amount of cancer cells that may still be in the body.

Standard chemotherapy after surgery will include a fluoropyridimine drug eg 5 Fluorouracil or Capecitabine as well as Oxaliplatin. Chemotherapy given in this setting will typically last 6 months. There is no current evidence of benefit in adding on targeted agents or immunotherapy.

STAGE IV

Depending on the extent of cancer spread, a minority of patients may still be cured or otherwise have their lives extended for a long period. It is important to have a proper assessment and discussion with doctors from different specialties eg surgeon, oncologist, gastroenterologist and radiologist before deciding on management.

Depending on the general condition of the patient, the symptoms the patient is experiencing as well as the extent of spread to other organs, surgery might still be considered if the patient is medically fit for surgery.

Early assessment of various biomarkers in the cancer cells is crucial. The important ones include KRAS, NRAS, BRAF and MSI. NTRK and other mutations may also be tested as part of a larger panel of molecular profiling.

In patients with recurrent cancers, it is best to have a repeat biopsy for testing of the biomarkers above, particularly if the period of time between the first and recurrent cancer diagnoses is beyond one year. The reason for retesting is that occasionally biomarker status can change over time.

In patients who do not require surgery, these may proceed to systemic therapy. Modern systemic therapy typically includes chemotherapy as a “backbone”, with the option of adding targeted agents eg Bevacizumab, Ramucirumab, Aflibercept, Cetuximab, Panitumumab and immunotherapy eg Pembrolizumab, depending on biomarker status. The precise sequence of the various combinations of systemic therapy may vary among oncologists.

For patients who have had several courses of systemic therapy and are sufficiently fit for further treatment, again it may be useful to have a repeat biopsy and this time to test for wider range of genetic mutations which may help the oncologist in selecting the most effective drugs for the next treatment.

For patients with limited areas of spread, surgery or other local ablative therapy eg radiofrequency ablation, cryotherapy, chemoembolisation, radioembolisation and precision radiotherapy, may be deemed appropriate to maximize control of the cancer. This may be recommended before or after systemic therapy.

There are patients who may decide not to proceed with active anti-cancer treatment or are otherwise unfit for treatment. Such patients will be offered best supportive care, to control symptoms and maintain the quality of life.

FOLLOW UP

It is essential for every patient to attend follow appointments as prescribed by the treating doctors. This is to allow doctors to manage both short term and potential long term effects of treatment, as well as to detect any recurrence of cancer as early as possible. Follow up assessment will include clinical history, physical examination, scans and/or blood tests.