> ASCO Update (Dr. Eric Winer, June 2010)
The annual meeting of the American Society of Clinical Oncology (ASCO) was held in Chicago from June 4-8, 2010. Each year, the ASCO meeting is the largest gathering of cancer professionals, with approximately 30,000 individuals in attendance. There were more than 100 presentations focused on breast cancer, including several studies that have the potential to change clinical practice.
A number of presentations addressed aspects of “local” therapy for women with breast cancer. By “local” therapy, we mean the treatment of the breast and lymph nodes (specifically those in the axilla).
A study from the American College of Surgeons Oncology Group (ACOSOG) looked at women with early stage breast cancer who had undergone a sentinel node biopsy. Those women with a positive sentinel node, meaning a sentinel node that contained cancer, were randomized to undergo a full node dissection or to have no further treatment to the axilla. For many years, the standard treatment for women with a positive sentinel biopsy has been to perform a lymph node dissection. Unfortunately, the study had to be closed early because the investigators had a difficult time recruiting patients to participate. Nevertheless, they found that women who did NOT undergo further surgery did as well as those who did. It would have been optimal to have a larger study so we could be more certain of the results, but the study suggests at least for some women with a positive sentinel biopsy, a full lymph node dissection is not necessary. We must be careful, however, before abandoning lymph node dissections. Women who had palpable lymph nodes (those that could be found on physical examination by a doctor) were not included in the study, nor were women with large tumors. In general, the women included in the study were at relatively low risk of having additional positive lymph nodes, and therefore the study results should not be applied to women who are at very high risk of having additional positive lymph nodes. That said, the study does open the door to avoid lymph node dissections for some women with a positive sentinel lymph node. As in all cases, this decision has to be individualized and needs to be made on a case by case basis after a discussion between a patient and doctor.
A second study from Dr. Kevin Hughes and the Cancer and Leukemia Group B (CALGB) looked at the long-term results in a group of women older than 70 who underwent a lumpectomy and were randomized to receive radiation to the breast plus tamoxifen or tamoxifen alone. With 12 years of follow-up, the study determined women who did not receive radiation were no more likely to die of breast cancer, have a recurrence of breast cancer in some other part of their body or undergo a mastectomy than those women who received radiation. Women who did not have radiation were more likely to have a recurrence in the breast. Nine percent of women who omitted radiation had a recurrence in the breast, whereas only two percent of women who had radiation had a recurrence. Nevertheless, since there was no difference in mortality or distant recurrence, the authors concluded many older women can safely avoid radiation. Importantly, these results only apply to women older than 70 who have small tumors (2 cm or less) and are taking tamoxifen or another hormonal therapy. For these women, however, omitting radiation is an option that should be discussed and carefully considered.
A third study presented by Dr. Kelly Hunt on behalf of ACOSOG looked at the way pathologists evaluate the sentinel lymph nodes in women with early stage breast cancer. This study examined the value of doing special stains to identify what are often called “isolated tumor cells”. For a number of years, there has been an active debate as to whether these isolated tumor cells have any impact on a woman’s prognosis and whether these special stains should be performed. The study found that isolated tumor cells did not have an impact on prognosis, and as a result of this study, pathologists should stop performing these special stains outside of a limited number of special circumstances. One such circumstance is the evaluation of the sentinel lymph nodes in women with lobular cancer. Unlike ductal cancers, it can sometimes be very difficult to detect cancer in the lymph nodes of women with lobular cancers and these special stains can be useful in this particular setting. For most other women, performing special stains on the sentinel lymph node will not provide useful information.
Finally, a study was presented that may provide a new option for women with advanced or metastatic breast cancer. Dr. Christopher Twelves presented the results of a clinical trial that compared a new chemotherapy drug, eribulin, to standard therapy in women who had received at least two prior chemotherapy regimens for their metastatic breast cancer. Eribulin is an agent that comes from a sea sponge, and like drugs such as paclitaxel (Taxol) and docetaxel (Taxotere), it can result in low blood counts and neuropathy. Unlike many other chemotherapy agents, it does not lead to severe hair loss in most patients. The study found women who receive eribulin had a 2.5 month median improvement in survival. While this improvement is modest, it is unusual for any drug in this setting to demonstrate an improvement in survival and it suggests for some women eribulin could be a beneficial treatment. At the present time, eribulin is only available in clinical trials, but these results could lead to an approval by the Food and Drug Administration. If eribulin is approved, doctors and researchers will have to sort out which patients are most likely to benefit from the drug and how it should be used in clinical practice.
The next major breast meeting is the San Antonio Breast Cancer Symposium in December, and many of us are very optimistic about some of the studies that are likely to be presented at that meeting six months from now. Month by month and year by year, we are clearly making steady progress, and it is my hope the progress will be greatly accelerated in the years ahead.