The American Society of Clinical Oncology (ASCO) held its annual meeting May 30 – June 3 in Chicago. At this year’s conference, there were three breast cancer related studies that drew extensive media attention. Here’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 post–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. We’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. It’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 don’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 studied—premenopausal, with hormone-positive cancer, and have had an oophorectomy or have been put into temporary menopause with a drug like goserelin—it may be worth considering. But for others, I think the best we can say is that, right now, we don’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 tumor’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.

Avastin’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, isn’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 can’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.

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4 Responses to ASCO 2008–Three Important Breast Cancer Studies

  1. Elaine Jesmer says:

    Few things make me angrier than researchers who think a drug will be “easier” on older patients. I’ll be 70 next year, and don’t want easy, I want effective. It was one of my concerns when I was going through chemo, because I had no side effects. I asked if that was because I was getting a lesser dose because of my age. Fortunately for me, that wasn’t the case. Incidentally, even though I was diagnosed at stage 4, after a 6-treatment course of chemo, I took Xeloda for 6 months. Xeloda gave me longer-lasting side effects than the first course of chemo. My point is, the patient, not the researcher, should be making the decision about what they can or can’t tolerate.

  2. gineblog says:

    Dear Elaine, I agree with you. The problem is that many researchers are working for the industry and the produced drugs have almost the same effect with different side effects. In fact, the therapeutic results did not change so much during the last 30 years. The better results are directly related with early diagnosis and clinical stage systematization. They (some doctors and the industry) are marketing drugs not treating patients.

    Conflict of interest: I am concern with women’s health and gynecologic cancer (http://www.ncbi.nlm.nih.gov/pubmed/18289805?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum)

  3. Debbie says:

    Thank you for the clear summary of these important findings. I’ll continue to follow your blog for future updates. As the community manager for LivingConversations.com, a site for breast cancer survivors, one of my jobs is to provide timely and accurate information for our founder to blog about or to add to our resource lists. This site is a great resource for me.

  4. csbruch says:

    Thanks to excellent doctors in Germany, Davis, and San Francisco, I have been on a bisphosphonate — clodronate — since 1998, one year after my treatment in CA for invasive breast cancer. An article in the 1998 New England Journal of Med reported Diehl et al.’s findings of reduced metastatic disease for women with node negative breast cancer who had tumor cells in their bone marrow. Because my invasive, aggressive breast cancer had been missed for at least 18 months, I had a bone marrow biopsy sent to Franfort for analysis and went there for care when a tumor cell was found. For years I imported my pills under prescriptions from my German doctor with the agreement of my US oncologist that were filled at 3-month intervals by a German pharmacy and shipped to me via FedEx. This was always difficult logistically, but completely legal under US law. The prescription was an off-label use of a drug for which osteoporsis is the on-label use around the world. (I did, coincidentally, have osteoporosis following my radiation treatments.) But a year ago, after I no longer had osteoporosis, my German oncologist recommended that I stop clodronate in order to avoid hypercalcemia. Later, as a maintenance dose, he recommended infusions of Zometa twice a year (at the dosage level ordinarily used for monthly infusions in osteoporosis cases), but my US doctors wouldn’t order the infusions. Apparently this was because it is off-label here, as was all my clodronate care. But this would have required them to write orders here rather than merely agree to my use of the drug and to monitor my health in connection with medications prescribed and purchased abroad. So I am now on 1/4 my original dose of clodronate and once again will be receiving my pills from Germany. My German oncologist and I know there’s no research on such continuing care (and it is unlikely there ever will be, he says, because this use would not make enough money for a drug company to inspire it to fund the research). But, because bone is continually broken down and rebuilt, we share the hunch that keeping my bones strong while avoiding hypercalcemia makes sense. If it has not already done so, I hope the FDA will soon give others in this country access to clodronate (Ostac 520 or Bonefos)to prevent metastasis. In 2007, it postponed a planned approval to wait for results of a 2008 report on large-scale US data. (I’m blanking on the name of that study.) How does that now look? And have the US clinical trials with clodronate (including its use for prostate cancer)been reported yet? If so, how have they turned out?

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