Here's a situation in which I learned something from the questions raised by people here online. A handful of people with extensive disease small cell lung cancer (ED-SCLC) in the last year or two have mentioned receiving radiation for areas of residual apparent disease after receiving initial chemotherapy. I had noted that I had never done this and didn't really see a clear rationale for pursuing a local treatment like radiation for a disease that has already declared itself as spreading throughout the body. But while there is no good evidence to say that radiation should be included after chemo, it is actually an open question, and there are some recommendations that say it's something to consider under certain conditions.

The question of whether radiation should be added routinely to chemo for ED-SCLC was the subject of several very old studies from 20-30 years ago, and they didn't show any clear benefit. However, radiation has changed a lot in that time, and in truth, several studies that compared chemo alone to chemo/RT were so small that they couldn't say anything meaningful. In fact, there was a single study published based on the combined efforts of groups in Germany and Japan (abstract here) that randomized patients who experienced a complete response (no evidence of disease) outside of the chest and either a complete or partial response in the chest to either additional chemo alone after platinum/etoposide chemo, or chemo and aggressive chest radiation. The results looked more facorable for the patients who received radiation in addition to chemo, although only 109 patients were included in the relevant analysis. Again, this was only in the patients who had a complete response and no evidence of cancer outside of the chest after initial chemo. As you might expect, radiation was associated with sometimes significant esophagitis (painful inflammation of the esophagus).

Unfortunately, I don't believe there's been any further assessment of this question presented or published in the last decade. Based on the rather scant evidence but some hint of a possible benefit, the American College of Chest Physicians has included in their evidence-based guidelines about managing SCLC (abstract here) that, while not a clear recommendation, it is reasonable to offer chest radiation to patients with ED-SCLC who have a complete response outside of the chest and a complete or partial response within the chest, acknowledging that this is a concept based on pretty weak evidence.

Still, I wanted to highlight this because it represents a situation in which I learned something new that will probably change my treatment approach, based on what people here described. I want to ensure that I'm open to new information and can not be wedded to just doing things the way I've previously approached them, if there is more information. In this case, the little information available goes back a long ways, but it suggests that it could be appropriate to be open-minded to the idea that "consolidation radiation" to the chest might be helpful even for extensive SCLC.