PET scans have become well established in initial staging of lung cancer and many other cancers, but another setting in which they may emerge as useful is in assessing response to treatment. Some oncologists and patients are already doing this, but the standard test most commonly used for measuring response is the CT scan, which is widely available and has the benefit of years and years of experience. We grade our work in oncology by looking for tumor shrinkage. The percentage of patients who have an “objective response” of tumor shrinkage by 50% is one of our key endpoints when we describe a treatment for cancer, but we now know that it is definitely very possible to have patients live longer without having major tumor shrinkage. Cancer without any treatment is definitely going to grow, so even keeping it stable in size can appropriately be considered a relative improvement. I’ll describe the evidence showing survival benefit in the setting of stable disease in a dedicated post soon.

But the issue here is the concept that either before a CT scan is able to detect changes in size, or in the event that there is no obvious change in the size of a cancer mass on CT, the PET scan may detect decreased or increased metabolic activity that can help us determine whether the treatment is helpful or futile. Even if nobody wants to learn that a treatment is ineffective, if it is causing side effects without the real promise of benefit, it makes sense to abandon that futile treatment earlier rather than later. And now that we have a growing number of treatments available for advanced NSCLC, we might consider it increasingly important to not waste our time, strength, and money on treatments that aren’t going to provide a benefit. Read the rest of this entry »