How Likely Is Cancer To Grow Back Once Treated?

It is one thing to get diagnosed with cancer, finding out which stage it is in, treating it through chemotherapy and then going through the traumatic experience after that. But the fear of cancer coming back again is an entirely different thing and could devastate the patient's morale and will power to a great extent. There are different reasons of cancers coming back. Sometimes, it can be the failure of the initial treatment in getting rid of all cancer cells. These cancer cells can create room for growth of a new tumour.

Another reason can be cancer cells spreading to other parts of the body and forming a tumour.

Reasons why cancer comes back after surgery

There are two reasons why cancer cells can come back after surgery. One of them is the possibility of some cancer cells being left behind during surgery. The other reason is that some cancer cells were there during the primary stage, but were too small to be seen.

Even though surgeons try their best in removing all cancer cells during surgery, there are always chances of some cancer cells being left behind.

Reasons why cancer comes back after drug treatment or radiotherapy

This again happens because all cancer cells were not destroyed during the treatment.

Chemotherapy drugs work in a way that they destroy cancer cells by targeting the ones which are in the process of doubling. However, all cancer cells do not divide in the same time. Just like other cells rest in between divisions, cancer cells rest too, but for a much shorter time. While chemotherapy works to destroy most cancer cells on their division, it is quite unlikely that it will destroy every single cancer cell in the body. The cells which remain after chemotherapy are destroyed by the body's natural defence mechanism and immune system.

Radiotherapy creates "breaks" in the DNA of cells. These "breaks" prevent growth and division of cancer cells, and also kill them. But when all cells aren't destroyed through radiotherapy, they can grow again as well.

Cancer drugs target at the factors which make cancer cells survive and grow. While some drug treatments completely destroy cancer, others may shrink the cancer or control them for months, sometimes even years. This may lead to no cancer been shown in scans or blood tests, but there may be small groups of cancer cells still remaining in the body. They are capable of regrowth after you discontinue with the treatment.

Cancers become resistant to treatment

There are times when cancer becomes resistant to treatment through drugs. Mutation in cancer cells can make them resistant to chemotherapy, cancer drugs or hormone therapy. Sometimes, the cancer cells become resistant to alternative treatment as well. This phenomenon is known multi drug resistance.

How can you prevent cancer regrowth

Experts say that regular check-ups are the most effective way of keeping regrowth of cancer cells at bay. "From the patient's side, we as treating oncologists want regular check-ups from the patient. For instance in case of blood cancer in children, the chemotherapy is divided in a total duration of 2 years. And in these 2 years, the initial 6 months include hospital-based intensive chemotherapy. Majority of the parents follow this treatment very strictly," says Dr Gaurav Kharya.

He goes on to add, "But once they reach the maintenance stage, (which is the next stage where the child has to just take oral chemotherapy and follow up every 2 weeks) majority of the parents fail there. Every drug has therapeutic window and if it is not able to reach that window, the chances of relapse are going to be more. Besides, a little bit of lifestyle modifications are suggested that can prevent regrowth of cancer cells. These include avoiding habits like smoking, alcohol consumption, chewing of tobacco, etc. In cancers where these factors are the causative agents, they must be avoided entirely post treatment."

(Dr Gaurav Kharya is Senior Consultant and Head, Pediatric Haemato Oncology and Bone Marrow Transplant, Artemis Hospitals)

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