Padmavati Prabhu
Panaji
Positron Emission Tomography-Computed Tomography (PET CT) plays a crucial role in treatment decision making of cancer, said Dr R V Parmeswaran, Chief of Department of Nuclear Medicine and PET CT, Manipal Hospital, Bengaluru.
“When PET CT started gaining prominence, a study was conducted on the extent to which the findings of a PET CT change the decision making in cancer treatment. The study showed that in 53% patients, decisions were changed after PET CT. It allowed clinicians to take more accurate decisions,” Dr Parmeswaran said.
Explaining, he said, “Consider we plan a surgery. Then we have to switch to chemo first, give a couple of cycles, repeat a PET CT and check the response. If the tumour, which is 10 cm, shrinks to 4 cm, it would be easier for a surgeon to operate. This is something called neoadjuvant treatment. A couple of cycles of chemo are given or maybe combined it with radiation therapy. So you understand the disease progress by using PET CT.”
Dr Parmeswaran was in Goa to deliver a talk on ‘PET CT in Current Oncology Practice’ organised as part of the 9th Annual Goa Cancer Society Lecture.
Dr Parmeswaran pointed out that in a current oncology setup, one cannot practice without PET CT. He said that PET CT has revolutionised cancer care by helping in diagnosing a disease and in monitoring response after treatment.
“PET CT is a combination of two imaging modalities. One can get the structural information from the CT, while the functional input can be obtained from PET, which is what all the clinicians want. Additionally, it avoids a lot of ambiguity, and both PET and CT are put together,” he said.
He said that PET CT can be divided into two main verticals – diagnosis and monitoring treatment.
“While mammography, colonoscopy, etc continue to be the routine diagnosing tools for cancer, the role of PET CT is to see if there is any regional involvement, structures involvement, or more importantly, distant metastasis, or we call it distant spread. Many a time, when the patient presents to a doctor with a clinical issue, though it may sound like an initial stage, it would have already spread to distant areas,” he said.
Stating that now the treatment paradigm is shifting, Dr Parmeswaran said, “Earlier it was just palliative. It was controlling the disease. But now the oncologists are talking about curing a disease. There is a lot of treatment regime which has come up wherein you control, curtail the growth of the disease and you give a good quality of life to patients which is more important. That’s where, in the diagnosis, PET CT comes in.”
He said that the next important thing is in treatment response evaluation.
“If a patient is diagnosed with cancer and started with a particular treatment, we need to check if the patient is responding to it. Many a time, a particular pattern or regime of treatment may not be the same for all patients. In PET CT, we give a value called standard uptake value (SUV). We quantify the disease and give it a value. The structure or size may not even change. But if the SUV value drops from five to two and a half, it means it is improved. So, we are objectively giving you a value and telling you that, this patient is doing well. It is actually a feel-good factor, not only for the patient, but also for the treating doctor. So, these are the two main verticals or the usage of PET-CT: diagnosing a disease and monitoring response after treatment. The third one is during follow-ups,” he said.
On an average, a PET CT costs anything between Rs 10,000 and Rs 25,000. Dr Parmeswaran expressed that in a government setup, there needs to be a facility for PET CT.
“Even a person who cannot afford such tests has got the right for good health. The government should have a look at it. The quantum or the percentage allocation for the healthcare sector should be increased,” he said.
When asked if every patient detected with cancer should undergo PET CT, he said, “The decision is with the doctor. But at some stage, a PET CT will be done. It may not be the initial diagnosis. Some of them may undergo at multiple steps. Some may undergo PET CT at diagnosis stage and the same patient undergoes it after three cycles of chemo or at follow-up. Many patients will have serial scans. If everything is fine, maybe in between scans, they’ll just do a CT, because if the doctor wants to look at only a particular area, why unnecessarily scan the entire body? So, that jurisdiction or the capability rests on the expertise.”
