The Balloon Theory vs. The Puddle Theory

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Should Pre-operative treatment lead to a change in the surgery done? The Balloon Theory vs. The Puddle Theory

http://blog.lungevity.org/2012/02/17/do ... oadjuvant/

February 17th, 2012 - by Dr. Jack West

One of the common scenarios we discuss in our lung cancer tumor boards is like a case we just discussed recently: a patient with a tumor near the middle of the chest and some nearby lymph nodes involved had a collapsed lung lobe; the lung surgeon thinks that because of the location of this cancer, the patient is likely to need the whole lung removed is surgery is going to be a realistic option with curative intent. This patient is a potential candidate for undergoing the rigor of losing his whole lung, based on his breathing tests, but we know that a pneumonectomy (removal of an entire lung) is a major loss, so a less extensive surgery would be attractive if feasible. This leads us to the question of whether, if we give pre-operative chemotherapy specifically with the intent of shrinking a cancer enough, we might be able to do a less extensive, lobectomy surgery (removeing one lobe instead of the whole lung), if an upfront pneumonectomy would otherwise need to be done. A similar question is whether it’s realistic to change someone from a nonsurgical candidate due to local extensive disease into a surgical candidate based on chemotherapy +/- radiation shrinking the extent of disease.

We don’t have a clear answer to this question. The idea of “downstaging” a cancer with neoadjuvant (pre-operative) chemotherapy or chemo/radiation is appealing, but there isn’t clear evidence that it really works. In the recently published ChEST trial that randomized patients to surgery alone or pre-operative chemo with cisplatin/gemcitabine followed by surgery, the recipients of chemo prior to surgery were less likely to have received a pneumonectomy (17% vs. 25%) and more likely to have undergone a lobectomy (70% vs. 60%) . However, the SWOG 9900 trial, with the same design but different chemo (carbo/paclitaxel) revealed no difference in the pneumonectomy rates with or without pre-op chemo — equal at 17% in either case. So how might we explain these discrepant findings?

Part of the explanation is likely that different surgeons have different : some have come to believe that a cancer is like a balloon, so that if it shrinks, you can presume that the new borders of the cancer don’t have extensions of viable cancer around them. If that’s the case, it should be possible to do a smaller surgery than you would have originally done — you can go from unresectable to resectable, or from needing a pneumonectomy to being able to receive lobecomy. But other surgeons believe that a responding cancer is more like as a puddle drying up in the sun: while the visible borders are tigher on repeat scans and even when directly visualized at surgery, you can’t be certain that there aren’t areas of living cancer beyond the visible cancer, extending out to where the cancer originally was. If that’s the case, you can’t pursue a less extensive surgery after pre-operative therapy if a person would have needed a pneumonectomy originally.

Therefore, the question of what surgery a patient actually gets is only partly a product of the surgery they appear to need on the most recent scans. We can’t rely on the potentially different rates of pneumonectomy vs. lobectomy being done to clarify whether all of the pneumonectomies were absolutely required or not. What we really need is a way to determine if the patients who were deemed to require a pneumonectomy that was then converted to a lobectomy do just as well as the patients who were anticipated to require a lobectomy from the beginning. But I don’t believe such data actually exist in the world at this time.

To give you a sense of how open this question is, I’ll share that I work with four excellent, board-certfied lung surgeons who work very well together but have their own different styles; in fact, with regard to this question, two of the four favor pursuing a smaller surgery after pre-operative therapy if a patient demonstrates a response to preoperative therapy, while the other two favor continuing with a plan of the original surgery that would have been required. And even with the same surgeon, we sometimes see differences. The surgeon who described his views on the case above favored pre-operative therapy to shrink the cancer for a patient we shared a few months ago who was going to need a pneumonectomy (and still did after the neoadjuvant chemo/radiation given), but for this more recent patient, the surgeon favored initial surgery with a pneumonectomy. In the more recent case, he wasn’t at all optimistic that the operative options would be better after chemo or chemo/radiation. He’s a great surgeon with terrific technical skills and good judgment, so to me these cases just illustrate how individualized patients and their cancers can be, with no “right way” for everyone, even with the same surgeon and team.