San Antonio Breast Cancer Symposium, Dec. 10-14, 2008
The 31st Annual San Antonio Breast Cancer Symposium took place Dec. 10 to 14 in San Antonio, Texas, and attracted about 9,000 attendees from more than 80 countries. The meeting featured 700 presentations and 1,400 abstracts that covered new and late-breaking research in experimental biology, etiology, prevention, diagnosis and therapy of breast cancer and pre-malignant breast disease, and also highlighted new findings from clinical trials.
"One of the themes is that we now have additional data from several adjuvant therapy trials to suggest that aromatase inhibitors are a little bit better than tamoxifen," said the president of the symposium, C. Kent Osborne, M.D., of the Dan L. Duncan Cancer Center at the Baylor College of Medicine in Houston. "There's also additional data to suggest that it might be better, at least in most patients, to start with an aromatase inhibitor rather than starting with tamoxifen."
Osborne added, "These trials might change practice. But none of these initial trials, which directly compare aromatase inhibitors with tamoxifen, has shown a survival benefit. So while I think there is a benefit, it's modest. In patients who can't tolerate an aromatase inhibitor, it's certainly not bad therapy to switch them to tamoxifen."
One of the most significant prevention trials presented at the meeting showed that an investigational SERM -- lasofoxifene -- was associated with a significantly reduced risk of breast cancer. "Furthermore, lasofoxifene did not increase the risk of endometrial cancer and was associated with a slight reduction in heart attacks," Osborne said. "If lasofoxifene is approved by the U.S. Food and Drug Administration, it could very well be a practice-changing drug."
During the five-year study, Andrea LaCroix, Ph.D., of the Fred Hutchinson Cancer Research Center in Seattle, and colleagues randomly assigned 8,556 women aged 59 to 80 with osteoporosis to receive lasofoxifene at dosages of either 0.25 milligrams or 0.5 mg per day, or placebo. Compared with placebo, the researchers found that lasofoxifene was associated with a significantly reduced risk of invasive and non-invasive estrogen receptor-positive breast cancers (hazard ratios, 0.52 and 0.19 for the 0.25 mg and 0.5 dosages, respectively) as well as a significantly decreased risk for all invasive breast cancers (HR, 0.79 and 0.15, respectively).
Stephen Johnston, Ph.D., of the Royal Marsden NHS Foundation Trust and Institute of Cancer Research in London, U.K., and colleagues presented the first results of a trial in which 1,286 postmenopausal women with hormone receptor-positive metastatic breast cancer -- including 219 who were HER2-positive -- were randomized to receive either letrazole and lapatinib, letrazole alone, or placebo. In the HER2-positive patients, they found that combination therapy was associated with a significantly increased median progression-free survival compared to letrazole alone (8.2 months versus three months) and a significantly higher overall response rate (27.9 percent versus 14.8 percent).
"This is potentially practice changing because a lot of clinicians prefer to treat HER2-positive patients with chemotherapy because HER2-positive status implies a degree of endocrine therapy resistance," Osborne said. "Because the combination therapy significantly prolonged the time to recurrence as well as the response rate, many clinicians may now consider using a hormonal therapy -- letrazole combined with lapatinib -- in that subset of patients instead of going straight to chemotherapy.
"An interesting secondary endpoint, which will not be practice changing, suggested that the combination therapy was also beneficial in a subset of patients who had previously received tamoxifen and were initially HER2-negative," Osborne said. "The hypothesis is even though they didn't have HER2 overexpression to begin with, they developed it over time because of the tamoxifen therapy and then responded to the lapatinib combined with the second-line endocrine therapy, which in this case was letrazole," he added.
"This is not a totally novel finding," Osborne said. "Two other groups, including my own, have hinted that this might occur in some patients. Now that several studies have shown this finding, it's probably worth investigating with a larger, more definitive trial."
One of the most widely reported studies presented at the meeting -- a new analysis of data from the Women's Health Initiative -- showed that breast cancer risk is doubled in postmenopausal women who take estrogen plus progestin for five years but that the risk declines to the level of non-users within two years of hormone therapy cessation.
"These findings suggest that cessation of estrogen plus progestin use is associated with a rapid reduction in breast cancer incidence, which is not explained by mammography utilization change, and support the hypothesis that the recent reduction in breast cancer incidence seen in certain age groups is predominantly related to a decrease in combined menopausal therapy use," lead author Rowan Chlebowski, M.D., of the Harbor-UCLA Medical Center in Los Angeles, and colleagues conclude.
This year's symposium is the first to include collaborative efforts of the American Association for Cancer Research, the Cancer Therapy and Research Center at the University of Texas Health Science Center in San Antonio, and the Baylor College of Medicine in Houston.
"The American Association for Cancer Research is delighted to have the opportunity to work with the Cancer Therapy and Research Center and Baylor College of Medicine in presenting this meeting to the breast cancer community," Margaret Foti, M.D., chief executive officer at the American Association for Cancer Research, said in a statement. "The San Antonio Breast Cancer Symposium is already an outstanding meeting. Clearly, the expert input of the American Association for Cancer Research enhances interactions between basic and clinical researchers."
SABCS: Anastrozole Shows Mixed Results in Breast Cancer
MONDAY, Dec. 15 (HealthDay News) -- After breast cancer patients undergo surgery and receive tamoxifen, switching to anastrozole may increase the likelihood of disease-free survival but also decrease quality of life. In addition, surgical patients who receive letrozole may have a lower risk of death compared to those who receive tamoxifen, according to research presented at the San Antonio Breast Cancer Symposium held Dec. 10 to 14 in San Antonio, Texas.
SABCS: Hormone Therapy Linked to Cancer Survival
MONDAY, Dec. 15 (HealthDay News) -- Among postmenopausal women who develop breast cancer, previous and current hormone therapy use -- particularly estrogen-progestin -- may be associated with a significantly decreased risk of death, according to research presented at the San Antonio Breast Cancer Symposium held Dec. 10 to 14 in San Antonio, Texas.
SABCS: Written Forms Double Breast Cancer Detection Rate
MONDAY, Dec. 15 (HealthDay News) -- During clinical breast examinations (CBE), the use of simple written forms to focus clinician attention may double the breast cancer detection rate, according to research presented at the San Antonio Breast Cancer Symposium held Dec. 10 to 14 in San Antonio, Texas.
SABCS: Genetic Test Predicts Breast Cancer Risk
FRIDAY, Dec. 12 (HealthDay News) -- OncoVue -- a new genetic-based risk estimator -- may more accurately predict breast cancer risk than the more commonly used Gail Model, which assesses conventional risk factors such as alcohol use, according to research presented at the San Antonio Breast Cancer Symposium held Dec. 10 to 14 in San Antonio, Texas.
SABCS: Tamoxifen's Effect on Breast Density Varies
FRIDAY, Dec. 12 (HealthDay News) -- In high-risk women who receive tamoxifen as a prophylactic treatment, reductions in breast density after 12 to 18 months of therapy are strongly associated with a reduced risk of breast cancer, according to research presented at the San Antonio Breast Cancer Symposium held Dec. 10 to 14 in San Antonio, Texas.
SABCS: Small, HER2-Positive Tumors Predict Relapse
FRIDAY, Dec. 12 (HealthDay News) -- Breast cancer patients with HER2-positive tumors that are 1 centimeter or less may have a significant relapse risk, according to research presented at the San Antonio Breast Cancer Symposium held Dec. 10 to 14 in San Antonio, Texas.
SABCS: Combo Therapy Shrinks Breast Tumors
FRIDAY, Dec. 12 (HealthDay News) -- When zoledronic acid is added to neoadjuvant chemotherapy in breast cancer treatment, it may have direct anti-tumor effects, according to research presented at the San Antonio Breast Cancer Symposium held Dec. 10 to 14 in San Antonio, Texas.