I mentioned a while ago that I had contacted Dr. Orin Bloch
about his research. As I’m going through the pre-surgery documentation to revisit the details now that we know more about what was in there, I thought you might be interested in an edited copy of his response with some relevant thoughts:
I’m sorry to hear about your tumor and the difficult decisions you must be facing. I hope that I can help by sharing some of my experience and opinion on the subject. Due to the location and invasive nature of chrondrosarcomas, tumors in the skull base are rarely completely resectable without neurologic injury. Some surgeons do attempt to remove the entire tumor, but it always comes at a price – specifically, injury to important arteries and nerves. This type of tumor is malignant by definition, but the specific pathology (grade and histological type) can suggest whether it will be fast or slow growing. If any tumor is left behind, it will likely eventually grow back. Even if it appears to be removed completely, a few microscopic cells may remain which can result in regrowth. As a general principle of oncology, any malignant tumor that is resected should be followed by adjuvant treatment (chemo or radiation – but chemo is not effective for chondrosarcomas) to sterilize the resection bed. The only exception is when negative margins of resection can be confirmed by histology, but this requires the tumor to be removed as a single piece which is not possible in the skull base. Dr. Almefty and his colleagues… advocate for complete surgical resection… In the paper you cited, they have a small patient population with an average follow-up of… 4 years. Because low-grade tumors grow slowly, most of them won’t recur in 4 years, but at 10 and 20 years it’s a different story.
Based on our review of a much larger body of literature, the data strongly suggests that adjuvant radiation is the single most important predictor of long-term tumor control and survival. The concerns about radiation injury are real, but just as your would pick a skilled surgeon to remove your tumor, you need a skilled radiation oncologist to plan the radiation without injuring the brain. Overall, radiation is far safer than aggressive surgery. As a surgeon, my approach to these tumors is to plan the maximal safe surgical resection with the intention of leaving some tumor behind if it cannot safely be separated from critical structures. I would always follow surgery with radiation, even if the pathology shows low-grade tumor. There is an option to follow any surgical residual and wait on the radiation until the tumor shows growth, but you might miss a critical window and the tumor can grow significantly between scans. The best time to treat these tumors is the first time. With regard to radiation, there is a school of thought that proton therapy is best, extrapolating from pretty weak data for chordoma (which is an entirely different tumor anyway). In truth, there is no data suggesting that one treatment modality is better than any other, and when the residual tumor is small enough, I prefer stereotactic radiosurgery. Radiosurgery delivers higher doses, sparing the brain to a greater extent, and is more convenient for patients since it is delivered in a single session.
In the end, my best advice is to pick the right surgeon and the right oncologist. These tumors are difficult and require appropriate skill and experience to treat. Make sure your surgeon has both and is planning the right operation with the right post-operative treatment. I wish you the best in this difficult time.” Bloch, 2015
Dr. Bloch’s research seemed really solid, based on my admittedly limited overview of the available articles about chondrosarcoma. I find it very persuasive, and the bulk of other articles support his conclusions. He’s in the minority in advocating for stereotactic radiosurgery, so that will require a bit more digging.