I just got back a couple of days ago from Chicago, where I attended the annual meeting of the American Society of Clinical Oncology (ASCO). This is an enormous meeting, attracting over 30,000 participants from across the country and around the world. All of the specialties involved in cancer care are represented – surgeons, medical oncologists, pediatric oncologists, radiation oncologists, social workers, psychiatrists, orthopedists, and others.
The annual meeting is an opportunity for researchers from around the world to present their findings to each other. I thought it might be interesting to discuss some of the interesting presentations about sarcomas that I saw:
Better Treatment for Ewing’s Sarcoma
One of the most exciting talks at the meeting (at least, for me) was Dr. Womer’s presentation of the results of the last Children’s Oncology Group clinical trial for patients with localized Ewing’s sarcoma. In this study, patients were randomly assigned to receive the same chemotherapy (cycles of vincristine/doxorubicin/cyclophosphamide alternating with cycles of ifosfamide/etoposide) every 3 weeks or every 2 weeks. The question was whether chemotherapy works better given closer together (time intensive), or whether there would be too many side effects. Well, the results are in, and time intensive chemotherapy works! The patients who received the chemotherapy every 2 weeks had a 78% 4-year event-free survival rate, compared with 70% for the patients treated at the standard 3 week interval. Although this improvement was limited to patients younger than 18 years old, this is probably because there were too few older patients to evaluate.
The Genetics of Rhabdomyosarcoma
Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of children and adolescents. There are several different types of RMS based on microscopic appearance, but the two most common types are called “alveolar” and “embryonal.” These types refer to the microscopic appearance of the tumors (alveolar because the tumor resembles the alveoli, or airspaces, of the lungs; embryonal because the tumor looks like very immature muscle cells). It has long been known that alveolar RMS is characterized by chromosomal translocations (where a piece of one chromosome is “swapped” for a piece of another one), but embryonal RMS is not. Dr. Barr presented data showing that embryonal RMS are characterized by specific changes in chromosome 11 instead.
Interestingly, not all alveolar RMS has these chromosomal translocations, and 63% of those that do not, instead have the same chromosome 11 changes seen in embryonal RMS. A detailed genetic analysis also showed that by this test, so-called “translocation negative” alveolar RMS appears to be more similar to embryonal RMS than to “translocation positive” tumors. This raises the possibility that, in the future, we may do away with tumor descriptions based on microscopic appearance in exchange for genetic descriptions that probably more closely reflect the underlying causes and behavior of the tumors.
One of the more rare types of sarcoma we treat is called synovial sarcoma. Doctors from the Rizzoli Institute in Italy looked back over the records of 250 synovial sarcoma patients treated there since the 1970’s to try to learn more about this rare disease. They presented some very important findings: 1) radiation therapy improves survival in patients with localized disease, but chemotherapy did not; 2) some patients relapse very late (more than 5 years from the end of treatment), suggesting that we need to follow these patients for a very long time; 3) patients who have a local relapse are often cured with further treatment, and it did not seem to matter whether this was a rapid relapse or a late relapse. This is an important study because it is the largest report on a single series of synovial sarcoma patients treated at a single institution.
Samarium to treat Osteosarcoma
Finally, I had the honor of presenting the results of my Phase I study of samarium-153 for the treatment of patients with osteosarcoma metastatic to bones. Samarium-153 is a radioactive agent that targets bone lesions. Because it was a Phase I study, the goal was to identify a dose of the drug we could give that would allow patients to recover safely and quickly from the side effects. Not only did we find what that dose is, but we also showed that this drug could be given to patients who had a LOT of previous treatment, and they had no more side effects than patients who had not been treated at all. Our next step will be to figure out how best to integrate this drug into treatment regimens based on chemotherapy, and hopefully one day this will be an important addition to our arsenal of therapies for osteosarcoma patients.
Unfortunately, my schedule did not allow me to make it to the presentation of the data regarding vitamin D and breast cancer, but you can read more about that study here.
Vitamin D and Breast Cancer
Osteosarcoma Symposium in Houston
Children's Oncology Group Meeting
Medicine from the Sea