Dr. Nasser Hanna, Indiana University Health, addresses the issue of prophylactic cranial irradiation (PCI) in locally advanced NSCLC.
Unfortunately many people with stage III disease are not cured of their cancer. We’re doing better, but we’re not doing good enough for most people and for those people who are not being cured, oftentimes the cancer will recur in what we call “distant sites.” That may be bones, it may be the liver, it may be the adrenal glands, these two small glands that sit above the kidneys, and sometimes it can be the brain.
When cancer progresses and shows up in the liver or shows up in the adrenal gland, it can certainly be disconcerting, sometimes it can cause symptoms and people don’t feel well, but oftentimes it’s something we just see radiographically. That’s oftentimes not true when cancer recurs in the brain. When it recurs in the brain, oftentimes it’s very unpleasant for somebody. They may have headaches, they may have double vision, they may have unsteadiness or nausea, they may pass out, they may even have seizure activity. So the idea of trying to prevent cancer from spreading to the brain is of paramount importance.
Now in another type of lung cancer, small cell lung cancer, we have utilized a strategy of prophylactically radiating the brain because we know that so many patients with small cell lung cancer eventually develop cancer in the brain. Prophylactically radiating the brain before any signs of cancer have appeared there may do one of two things. Number one is there actually may be microscopic disease in the brain that we really can’t detect on imaging studies for which you’re radiating when you’re doing the so-called prophylactic brain radiation. Secondly, some people believe that when you radiate the brain, it forms sort of an inhospitable environment for cancer to subsequently implant and seed. Either way, we’ve demonstrated that in patients with small cell lung cancer, you can reduce the incidence of brain metastases and in some cases actually help people live longer if you prophylactically radiate the brain.
Now the incidence of brain metastases in those with stage III non-small cell lung cancer is not as high as those with small cell lung cancer. Having said that, about 30-35% of those with stage III disease do eventually develop brain metastases. So the question has come up: should we or could we prophylactically radiate the brain and achieve fewer brain recurrences and perhaps maybe even help people live longer or cure more disease? Well the answer to this question is really unknown — there was one attempt at a carefully conducted clinical trial to test this idea, and unfortunately it was very difficult to accrue to this clinical trial, and it ended up only accruing about a third of the patients that it was meant to accrue.
We got some limited information from this clinical trial and what we learned is yes, we can reduce the incidence of cancer appearing in the brain by prophylactically radiating it. We really weren’t able to demonstrate in this small group of patients an ability to cure more people or help more people live longer, and certainly prophylactically radiating the brain does come with some side effects such as hair loss, fatigue, sometimes headaches, and sometimes nausea.
As of today, it is not standard to prophylactically radiate the brain in patients with non-small cell lung cancer and I’m not sure we’re ever going to get the completion of a clinical trial that will adequately address that, so I suspect for now and probably forever that will not be a standard approach for patients with stage III disease.