Adjuvant chemotherapy and bowel cancer: everything you need to know

Leading consultant medical oncologist Dr Aspasia Soultati explains adjuvant chemotherapy, including how it differs from traditional chemotherapy and which specific types are used for bowel cancer.

What is the difference between chemotherapy and adjuvant chemotherapy?

Whenever someone is diagnosed with bowel cancer, the most important question is whether the surgeon can remove the cancer with clear margins. Once the cancer is removed, your surgeon will refer you to an oncologist to have a discussion about the role of adjuvant chemotherapy.

Adjuvant chemotherapy is chemotherapy that is given after an operation to reduce the risk of cancer returning. An oncologist, along with your surgeon, will review the histology of what was resected and will try to identify risk factors in the histology such as t4 disease, poor differentiation or most importantly, if lymph nodes are involved. If those risk factors are present, it increases the risk of cancer coming back in the future.

My patients often ask me if their cancer will return and where in the body it can return. The truth is that it could come back to the lungs or liver, in which case it may be incurable.

For this reason, we try to assess the tumours that are at a higher risk of coming back and subsequently, which will benefit from additional treatment, which will try toreduce the risk of the cancer coming back. It is named ultraviolet chemotherapy and is used to try and eliminate cancer cells that the surgeon cannot reach or see well.

Ultraviolet chemotherapy does not guarantee that the cancer will not return, however, it can reduce the risk of this happening significantly.

The benefit of this therapy for each patient will depend on how many risk factors there are in the histology and what the histological staging is.

Patients with lymph node disease usually have been offered chemotherapy as adjuvant. The benefit is that this chemotherapy will give around a 15 to 20% reduction in the risk of relapse for all patients with no positive disease.

Patients may also be offered adjuvant chemotherapy if they have stage 2 disease but with some more risk factors such as default disease or differentiation in which case the benefit from chemotherapy is estimated to be lower. It is estimated to be 3-5% and is only for patients with MSI (microsatellite instable) normal and is for patients who have a specific DNA profile in their tumour.

It is essential to have a very thorough discussion about the risks and the benefits of adjuvant chemotherapy with your oncology consultant when considering the treatment.

You will be offered adjuvant chemotherapy depending not only on the histological characteristics of the cancer and the risk factors, but also on fitness levels and accompanying comorbidities. This is because the most common chemotherapy given as adjuvant for bowel cancer is CAPOX chemotherapy and the risk of developing any side effects from the treatment is linked to the patient’s performance status and comorbidities.

At what stage of bowel cancer is adjuvant chemotherapy used?

Adjuvant chemotherapy is used in two cohorts of patients. The first cohort is stage B bowel cancer, where there is t3t4 and 0 disease, with risk factors such as poor differentiation, presentation with obstruction of perforation as an emergency, and any t4 disease.

In these patients, when we are deciding whether they are eligible for adrenal chemotherapy, we perform a special DNA test on the histology called MSI, because if patients have a specific DNA change that we call microsatellite instability,  then their prognosis is really good and we don’t offer adjuvant chemotherapy.

For the patients whose msi is normal, we discuss the role of adjuvant chemotherapy for these patients with risk factors and stage 2 disease.

We also offer adjuvant chemotherapy in all patients with stage C colorectal cancer which is essentially all the patients that have positive lymph node disease. In these patients, we discuss adjuvant chemotherapy, provided that the patients are well and fit enough to receive it, 

What type of adjuvant chemotherapy is used for bowel cancer?

The most common type of adjuvant cancer therapy that we use for bowel cancer is three months of CAPOX chemotherapy.

The patient’s performance status and comorbidities along with the stage can define whether they will require three months of chemotherapy and what form of chemotherapy. Additionally, they may be offered monotherapy with capacitability or even FOLFOX chemotherapy, depending on fitness levels and the stage of the disease.

There has been a recent large study demonstrating that three months of CAPOX chemotherapy appears to be the optimal treatment option for scuh cases, but the oncologist may recommend six months of chemotherapy if monotherapy is suggested, or if the disease is very high risk.

How effective is adjuvant chemotherapy?

The benefit that chemotherapy confers in patients with stage C disease with positive lymph nodes is a 15 to 20% reduction in the risk of relapse. For patients with stage B disease who have risk factors but no involved lymph nodes, the benefit of adjuvant chemotherapy is smaller and is usually in the range of 3 to 5 % reduction in the risk of relapse.

What are the associated risks of adjuvant chemotherapy?

Chemotherapy is not an easy treatment. Before commencing chemotherapy, usually with auxiliary blood, you will be offered the DPD test by your oncologist, which is a blood test that enables us to see whether the enzyme that metabolises the drugs in your liver works correctly.

If the enzyme does not work 100% correctly, your oncologist will have to reduce the role of chemotherapy in order to avoid escalation of side effects.

Chemotherapy with this combination usually has a 30 to 40% chance of side effects such as allergic reactions, neuropathy, numbness and tingling in the fingertips.

It can cause extreme sensitivity to the cold, therefore you should avoid eating cold things, drinking cold water, and touching cold things. In addition, it can cause neutropenic sepsis, which is a life-threatening infection. The fever can cause nausea, tiredness, diarrhoea, a painful rash in the hands and feet.

Very rarely, it can be linked to a spasm in the heart but this is usually linked to those who have pre-existing heart conditions. It can also be linked to blood clots.

If you are suffering from bowel cancer and would like to book a consultation with Dr Soultati, do not hesitate to do so by visiting her Top Doctors profile today.