Mar 25, 2013 - 9:46 am
I started this new thread because I thought this was an interesting topic ... it was brought up in AHelstrup's message. Thought some might be interested. Wishing everyone the best. -- Cynthia
.... But let’s get back to the launching off point for this post. Does any of this mean that there’s any truth to the contention that operating on tumors somehow results in its spread? Not really. For one thing, there’s little evidence in humans that this happens. (Once again, humans are not mice.) For another thing, the presence of microscopic metastases is the very rationale for adjuvant chemotherapy given after surgery for many cancers; the chemotherapy “mops up” the microscopic tumor deposits that might otherwise grow into macroscopic metastases. For another thing, even if removing the primary tumor in humans actually did “release” micrometastases from growth inhibition in many human cancers, the option of leaving the primary tumor in place is not a good one. It will keep growing and ultimately cause complications, and eventually the metastases will escape growth inhibition anyway. Also, if metastases pop up after surgery, they were almost surely there before the surgery, too small to be detected on preoperative imaging studies, and not “spread” from the primary tumor by the surgery or by oxygen hitting the tumor. As is so often the case, correlation does not necessarily equal causation. Finally, it is possible to seed tumor cells by surgery to nearby areas. (It is not possible to seed tumors to distant organs that way, because this is purely a mechanical spreading of tumor cells.) Recurrences of colorectal cancer showing up at the port site after laparoscopic surgery were once a big concern early in the history of the procedure until data was obtained to show that the rate is actually quite low. In any case, attention to careful surgical technique goes a long way to prevent tumor seeding.
In the end, the only modality that has any chance of curing most solid tumors is complete surgical extirpation of the primary tumor with a healthy margin of normal tissue around it. (One exception is anal cancer, where radiation and chemotherapy alone, a.k.a. the Nigro protocol, can be curative.) After that, radiation and chemotherapy are just icing on the cake that decrease the rate of recurrence. Without surgery, there would be precious few survivors of any solid malignancy, and it would be foolhardy to deny oneself a chance at a surgical cure based on what is, in essence, theoretical possibility for which the evidence is quite sketchy. Thus, when patients ask me the question described, I answer that there is no good evidence that surgery causes tumors to spread and lots of good evidence that surgery is the best treatment.