Personalised Cancer Treatment and Next Generation Sequencing Explained

It is not available for everyone blanketly — you first need to identify the target on the cell, which is where NGS and special staining come in. Not every individual harbours those targets, but many do, and we then use specific targeted drugs. Immunotherapy is not available for all cancers either, but with present indications it is available for the majority of advanced cancers — about 70% of advanced cancers would be candidates for some form of immunotherapy. There are specific criteria that must be met; giving it without meeting those criteria would not help the patient and would just be a financial waste.

We take a biopsy from the specimen, cut it into sections, make blocks, and apply immunohistochemistry staining, which lets us identify targets on the cells. We then do mutation testing to see what mutations are present in the genes, to identify further targets we can address. We also do PD-L1 testing, which tells us whether the patient can receive immunotherapy. It is a combination of these staining protocols along with NGS that tells us the best way forward for the patient.

We take the biopsy specimen and extract the DNA from the cancer cell, then sequence it to identify where something has gone wrong in the DNA or RNA, which tells us why that individual developed the cancer. Through this we identify specific mutations that may be the probable reason. Research is ongoing to counteract every change found on NGS, but currently we have a few drugs available for certain specific mutations — if we find one of those, we give that specific drug and the patient benefits.

If you don't have a PET-CT, the second-best modality is a CT scan of the probable areas — chest, abdomen, and maybe head and neck depending on the cancer — which will give some answers on staging. As for treatment: chemotherapy is calculated as per the height, weight and profile of the patient, not given as a simple fixed dose. There are specific mixing criteria — it cannot be mixed like an antibiotic — and India has specific mixing units where care is taken over contamination and dosing. Drugs also have to be given over an appropriate infusion time, since infusing over the wrong duration causes more side effects. We also have monitoring systems running during chemotherapy to catch problems early, and targeted therapies and immunotherapies have specific temperature and light-sensitivity handling requirements that are important to follow correctly.

Previously it used to take 30 days, and it still does in most institutes, but with the advanced machines we now have, our turnaround time is only about five to six working days — even including a Sunday, a comprehensive NGS report is usually ready by about the seventh day.

Because treatment targets that individual's specific tumour biology, not just the cancer type and stage. Testing such as next generation sequencing identifies the genetic driver behind each patient's disease, so identical diagnoses can call for different treatment plans and produce different outcomes.

It extracts DNA from the patient's tumour cells and analyses it to identify the genetic changes, or switches, that led to that individual's cancer developing, so a matching drug can be used to block further growth.

Because some cancer cells may remain alive in the body even after treatment looks complete, which is why ongoing monitoring stays an important part of care after the initial course of treatment ends.