Cancer experts from around the world gathered in Chicago the first week of June to share the results of research studies. Although the ASCO meeting covers the entire scope of oncology, there are usually major breast cancer findings reported, and this year was no exception. In fact, two out of the five main presentations mentioned below focused on large breast cancer clinical trials
Findings from the ALTTO study, a multinational study, co-led by Komen’s 2013 Brinker Award Winner Dr. Edith A. Perez, were reported for the first time. The study enrolled over 8,000 women with HER2-positive breast cancer who had recent surgery and were about to start chemotherapy (adjuvant therapy
). The researchers compared:
- Chemotherapy + trastuzumab (Herceptin)
- Chemotherapy + lapatinib (Tykerb)
- Chemotherapy + trastuzumab + lapatinib
Much to the surprise of many, combining trastuzumab with lapatinib was not better than trastuzumab alone in reducing recurrences
of breast cancer, and the two-drug combination was significantly more toxic. (However, the vast majority of the women in the trial did well and there were few breast cancer recurrences overall.) Because trastuzumab alone has so many fewer side effects than trastuzumab plus lapatinib, it is unlikely that the two-drug combination will ever be used to treat early breast cancer. But, there still remains a role for lapatinib in the treatment of women with advanced or metastatic breast cancer. Clinical trials are also continuing to look at other anti-HER2 drugs for early breast cancer. Although the results for treatment with chemotherapy plus trastuzumab are excellent, there still are women who face recurrences and we would ultimately like to omit chemotherapy altogether. With these two challenges in mind, we very much need to develop new and better drugs.
The TEXT and SOFT studies also provided important results. These studies evaluated the role of ovarian suppression in women with hormone receptor-positive breast cancer. They compared:
- Ovarian suppression + tamoxifen
- Ovarian suppression + an aromatase inhibitor
Of note, all women in the study were premenopausal and all received ovarian suppression medication to “turn off” the functioning of their ovaries. With this medication, these premenopausal women became the equivalent of postmenopausal women, and many had significant side effects. In addition to the ovarian suppression, women received either tamoxifen or an aromatase inhibitor. Although there was no difference in mortality (death) through five years of follow-up, the investigators found that women who received an aromatase inhibitor were less likely to have a recurrence of breast cancer. At this point, the interpretation of the trial remains somewhat controversial. Because the standard treatment approach in the U.S. is tamoxifen alone, many doctors are hesitant to change that standard at this point, largely because the combination of ovarian suppression and an aromatase inhibitor is so much more toxic than tamoxifen alone. Some doctors may opt for this approach in women at particularly high risk of a recurrence, and many others are waiting for the results from an additional analysis of the data that will help tease out the role of ovarian suppression when combined with tamoxifen. Making the matter more complex, a previous study found that ovarian suppression plus tamoxifen was superior to ovarian suppression plus an aromatase inhibitor. Although that study was smaller than the analysis of TEXT and SOFT, it troubles many doctors when two studies so clearly disagree with one another and leads to greater reluctance to change practice. Of interest, European doctors may be more inclined to change practice, largely because they have accepted ovarian suppression as a standard treatment for many years. Premenopausal women with hormone receptor-positive breast cancer should know that tamoxifen alone still remains reasonable, but now there are other options. In the months and years ahead, the option of ovarian suppression plus an aromatase inhibitor may be used more commonly. For the time being, most U.S. doctors are opting for a “wait and see” approach with the plan that if they start or continue a patient on tamoxifen, they can always make a change in the future.
Many other researchers presented data at the ASCO meeting. There was new information about several classes of drugs including the PI3 kinase inhibitors and the CDK 4/6 inhibitors. Although none of these drugs are ready for widespread use, they are undergoing active and rigorous evaluation in clinical trials. These drugs, as well as many others, provide great hope for the future. In recent years, the pace of progress seems to have accelerated, and each and every year there seems to be something new that can truly have an impact on the lives of women (and men) with breast cancer.