PET scans are an important way to discriminate between metabolically active nodules, suggestive of cancer but sometimes representing inflammation or infection, and non-PET-avid lesions that are felt much likely to represent cancer. They are also a cornerstone of "clinical" staging by imaging and patient exam (vs. "pathologic" staging by surgery to clarify where cancer is or isn’t).
Among the many variables that can potentially be helpful in predicting outcomes after surgery are some imaging results. One of these is cavitation, or hollowing out of the inside of some part of the tumor. Although most clinicians think of this as a feature of squamous cancers, it can also be seen with adenocarcinomas and other histologies less frequently.
Purists have considered mediastinoscopy, which is invasive staging of the mediastinum through a small incision just at the base of the neck to get down behind the sternum, or breastbone, to be the "gold standard" for determining whether lymph nodes in the mediastinum, or middle of the chest, is involved with a cancer. The procedure is as shown:
Well, as I suspected, the topic of lung cancer cancer screening has been a bit of a minefield, but I'm going to end now by trying to pull together where we are here and now, at least in the US.
The topic of lung cancer screening is a very charged one, with most people, patients and physicians alike, having a strong opinion, either for or against. This is also an area in which there can be suspicion that any argument against screening is due to a financial calculation in which saving people from lung cancer isn't worth the cost of imaging. Any screening discussion also entails a consideration of cost, financial and other, vs. benefit, but here I'll focus on the issues related to the possible shortcomings of lung cancer screening in terms other than cost.
The issue of CT screening for lung cancer is a big one, and to handle it properly I'm going to write about it in a few installments. It's also quite controversial, so today I'll start with the reasons in favor of CT screening. Just by means of background, I'll start by saying that chest x-rays have been studied for screening, but they don't provide enough detail, requiring tumors to be larger before they are reliably detectable, and location of the tumor can be a problem.
In my last post, I described our evolving recognition in the lung cancer field that significant response as the threshold for clinical benefit is too high and that stable disease is likely a relative benefit as well. An important trial presented by Dr.
Thus far, the vast majority of patients who have an initial response to EGFR tyrosine kinase inhibitors like Iressa and Tarceva will eventually become resistant to them.
Right now we use the same conventional staging system for BAC as with other lung cancers. I don't have a great alternative just yet. I can tell you that as the lead investigator on several BAC trials, there are huge differences in the natural history of their cancer, regardless of what our treatment does.