The American Society of Clinical Oncology (ASCO) held its annual meeting May 30 â€“ June 3 in Chicago. At this yearâ€™s conference, there were three breast cancer related studies that drew extensive media attention. Hereâ€™s what you need to know:
Zoledronic Acid (Zometa) Reduces Recurrence
Researchers presented data from a study that found that giving zoledronic acid (Zometa), a bone building drug, to premenopausal women undergoing ovarian suppression and hormone therapy significantly reduced the risk of recurrence in early-stage breast cancer.
What You Need to Know: This study included 1800 women. All had already had surgery to remove the tumor. All received goserelin to suppress ovarian functioning. Half of the women received tamoxifen and the other half received anastrazole (Arimidex). Half of the women receiving tamoxifen and half of the women receiving anastrazole also were given an infusion of zoledronic acid every six months for three years. (Zoledronic acid is a bisphosphonate that is currently used to treat patients with bone metastasis, and was recently approved for osteoporosis treatment in postâ€“menopausal women.) The researchers followed the women for five years.
Important points: None of the women in this study received adjuvant chemotherapy. They all had hormone therapy. At five years, 137 women (7.6%) had had a recurrence, while 42 (2.3%) deaths occurred. This means this study found a 98% chance of survival in young women who are given ovarian suppression and hormone therapy drugs but do receive any chemotherapy. This aspect of the study garnered less media attention, but it certainly supports those who have made the argument that many young women are being overtreated with chemotherapy.
Also, the study found that there was no difference between in recurrence risk in the women who took tamoxifen and those who took an aromatase inhibitor. Weâ€™ll need to wait for the larger studies comparing the two hormone therapies in premenopausal women to see if this holds up, but it underscores that tamoxifen remains an important treatment option.
Now, to the zoledronic acid: In the group that got the bisphosphonate: 39 had a recurrence and six developed contralateral breast cancer. In the group that did not, 61 had a recurrence and 10 developed contralateral breast cancer. This is a 36% reduction in recurrence. And it was statistically significant, meaning that it is highly unlikely to have happened just by chance. However, there are also side effects to consider. And with zoledronic acid the most serious is an increased risk of developing osteonecrosis of the jaw. The researchers monitored the women closely and no cases were seen, but it is still a potential concern.
There are probably many women who read about this study and made an appointment to ask their doctor if they can go on zoledronic acid too. Itâ€™s important to note that this study was done in premenopausal women who were on hormone therapy to suppress ovarian function. The findings may not hold true for hormone negative cancers, which are less likely to spread to the bone. We also donâ€™t know if the findings will be true for postmenopausal women. Or for premenopausal women who are on hormone therapy but not taking goserelin or who are treated with chemotherapy and hormone therapy.
However, if you are part of the group that was studiedâ€”premenopausal, with hormone-positive cancer, and have had an oophorectomy or have been put into temporary menopause with a drug like goserelinâ€”it may be worth considering. But for others, I think the best we can say is that, right now, we donâ€™t yet know enough to recommend it widely.
Bevacizumab (Avastin) and Breast Cancer
Researchers presented data from a study that found that adding bevacizumab (Avastin) to docetaxel (Taxotere) slows disease progression in women newly diagnosed with locally advanced or metastatic breast cancer. This study adds to previous findings on bevacizumab for treating breast cancer.
What You Need to Know: Bevacizumab (Avastin) is an angiogenesis inhibitor. It works by cutting off a tumorâ€™s blood supply. This Phase III trial enrolled 736 women in 24 countries. All were HER2-negative. None had received prior therapy for metastatic disease. All of the patients received Taxotere. Half were randomly selected to receive Avastin; the other half received a placebo. Among those in the Avastin group, half received a low dose and half received a high dose.
The researchers found tumor reduction in 44.4 percent of patients treated with Taxotere and a placebo, against 55.2 percent for those treated with Taxotere and a small dose of Avastin, and 63.1 percent for those treated with Taxotere and a high dose of Avastin. No significant side effects were reported.
Earlier this year, the Food and Drug Administration approved Avastin as a treatment for breast cancer. The decision was controversial because there was no evidence that the drug extended overall survival, only that it slowed the progression of the disease. In addition, not only did Avastin result in more side effects, but it also was responsible for 5 of the 363 deaths that occurred during the study.
Avastinâ€™s approval again brought to the fore the question about what the criteria should be to approve new cancer drugs. If a drug delayed progression but had no side effects you could argue that there is a benefit because the drug is lengthening the amount of quality time that a person has, even if they die at the same time. However, if a drug delays progression but also has more side effects, then we must ask the question: Is it worth it? This is a personal decision that every breast cancer patient will have to make with her doctor.
Capecitabine (Xeloda) in Older Women with Early Stage Breast Cancer
Researchers presented data from a study that found that standard chemotherapy was more effective than the oral chemotherapy drug capecitabine (Xeloda) in older women with early stage breast cancer.
What You Need to Know: This is a surprising finding. Capecitabine (Xeloda) is an oral drug approved for the treatment of metastatic breast cancer or breast cancer that has recurred after other treatments. The body converts it into 5FU, a drug used in many breast cancer chemotherapy regimens. The researchers thought that giving older women an oral agent would be easier on them than having them undergo intravenous chemotherapy.
Their study included 633 women with early-stage breast cancer who were 65 or older and who had already had surgery to remove their tumor. Half of the patients received standard chemotherapy; the other half received capecitabine. After following the patients for about two years, the researchers found that the patients who had received capecitabine were significantly more likely to suffer a relapse and more likely to die than those receiving the standard treatment.
Why this would be the case, isnâ€™t clear. When new breast cancer drugs are introduced, they are typically first tested in the metastatic setting. Only after they are found to be effective there do we being studying whether they are effective in treating early-stage disease. This finding reinforces that we canâ€™t assume that drugs that prolong disease-free survival in the metastatic setting will be effective in treating early-stage breast cancer. Others studies are now underway that are looking at capecitabine as an adjuvant treatment for early-stage breast cancer, either alone or in combination with other drugs. Everyone will be watching these studies closely.
To view all the ASCO conference abstracts, click here.