Sandhya Raghavan
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Radiotherapy is a form of non invasive cancer treatment (except Brachytherapy) wherein focussed energy such as ionised radiation is used to target malignant cells in the body. The radiation helps in breaking down the DNA of the cancer cells to keep them from proliferating. Cancer cells eventually shrink in size or die a natural death. Radiotherapists work with utmost precision to ensure that radiation is directed only towards the malignant cells. In this respect, radiation therapy differs from chemotherapy in its ability to isolate cancer cells without harming the healthy cells that surround them. Radiotherapy remains a local form of treatment though rarely it can be used as systemic therapy.
Despite its many salient features, radiotherapy invokes fear in a lot of patients mainly due to the stigma surrounding its workings. But advancements in the field offer a lot of promises in the treatment s efficiency and its ability to mitigate post-therapeutic side effects in patients. In this exclusive interview with leading doctor of radiotherapy and oncologist Prof. Y Indibor Singh from the Regional Institute of Medical Sciences, Imphal talks about whether radiotherapy is touted to be the future of cancer care in India.
These days, doctors study the patient s genetic makeup to strategise what kind of treatment would be more effective for him or her. What are thoughts about personalising radiotherapy treatments to suit the requirements of patients?
We are now living in an era of personalised treatment of cancer, be it chemotherapy, biotherapy or radiotherapy. Personalised radiotherapy or smart radiotherapy is new but upcoming. Once we learn about radiobiology, and prognostic biomarkers of radiosensitivity and radio responsiveness in patients, we will be able to understand which patient will be able to benefit from which therapy. The radioisotopes will be able to search the cancer cells selectively and kill them. For example, Samarium-152, a radioisotope can find cancer cells in bone metastasis and selectively knock them out. Similarly, iodine-131 selectively kills thyroid cancer cells. In such a scenario we can say that radiotherapy can be used as targeted therapy. On the other hand, we have identified and developed biomarkers both prognostic and predictive which can guide us in deciding the right type of tumours and dosage for therapy. This is what personalised radiation therapy is all about. However much remains to be done (clinical trials ) before we validate the markers for routine clinical use.
A lot of effort is being put in improving the accuracy of radiation therapy treatment these days. Image-guided radiation therapy (IGRT) is one of the results of that effort. Could you explain IGRT works?
IGRT is another technique that focuses on the precision delivery of radiotherapy. By using linear accelerator based equipment (high-energy x-rays meant to target only the tumour and not the neighbouring cells), we can deliver highly conformal radiotherapy to the target volume (3-D CRT). In IGRT treatment the unit incorporates an imaging system which tracks the patient's movement, position and target movement in real time. Hence we call IGRT 4-D treatment. This helps in the precise delivery of radiation. Nowadays, we have also helical tomotherapy (x-rays that target the tumour from different directions) and TrueBeam therapy (x-rays that rotate around the body to target the tumour from every angle), which gives high accuracy in radiation beam delivery. A salient feature of IGRT is that the patients do not have to hold their breath during the therapy. The image guidance system will automatically track the tumour and target it. We call it ART (Adaptive Radiotherapy) when the target volume is shrunk as the tumour shrinks.
How do you propose radiotherapy should work towards improving the quality of life of the patients?
If we can deliver radiation in such a way that almost all normal cells are spared and only the cancer cells are killed, the radiotherapy sequelae (after effects of the therapy) will be less, and the patient s quality of life won t be compromised too much. But a lot of patients fear radiation because of its acute and late reactions. Modern units are addressing these issues, and the way we deliver radiation is much better from how we did one or two decades ago. We now have high energy beam; linear accelerators; and highly conformal therapy in 3D, 4D, 5D and even 6D. We also have stereotactic radiotherapy in which we use non-invasive tools such as Cyberknife or gamma knife especially suitable for intracranial tumours as well as in liver and lung when tumour size is less than four cms in diameter. Brachytherapy, a form of advanced cancer treatment, can deliver high doses of radiation to specific targets. These advancements will undoubtedly improve the quality of life of the patients and treatment outcomes will be much improved. Another exciting field is that with the help of biological imaging techniques PET-CT scan we can deliver biologically conformal radiotherapy.
What are some of the side effects that these treatments can help avoid?
As I have said, the principal of radiotherapy is to deliver maximum dose to target volume and minimum or nil to normal tissues (If that is possible). Only then can the post-therapy side effects will be acceptable, and the patient will have a good quality of life. For example, if I can spare the parotid glands during radiation therapy of oral cancer patient, then he may not experience the dreaded xerostomia or dryness of the mouth which compromises the patient s quality of life. Sparing of parotid glands can be easily achieved with the help of Intensity-modulated radiation therapy.
How cost-effective are these treatments?
All these modern, sophisticated radiation treatments come at a price which I believe may not be very affordable in developing or underdeveloped countries, and technologies are becoming outdated very fast. The most advanced technology of today may therefore not mean anything to the poor and needy patients of our country by tomorrow. So it remains out of the reach of the majority of poor patients.
What new improvements can we expect in the field of radiotherapy in the years to come?
In the coming ten years, radiation equipment will be upgraded in the light of molecular and metabolic imaging (it can differentiate viable and necrotic cancer cells in the target volume) and deliver radiation accordingly. The dose will be prescribed according to the radiobiology of the target. We will see the use of particle beam therapy like heavy ion beam therapy and proton beam. The latter has already been started in Chennai.
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