Highlights From ASCO 2012 Breast Cancer Symposium

TON - October 2012 Vol 5 No 9 published on November 19, 2012 in Conference Correspondent
Caroline Helwick

The American Society of Clin­ical Oncology 2012 Breast Can­cer Symposium, held September 13-15 in San Francisco, California, offered all members of the cancer team an upfront view of new data and an opportunity for one-on-one interaction with experts in the field. The following are a few re­search items of interest to oncology nurses.

Barriers to Mammography Screening Among the Underserved
Despite the provision of free services, fear of cost, fear of procedural pain, and fear of abnormal findings remain barriers to mammography screening among medically underserved women, according to research from Washing­ton University School of Medicine, St. Louis, Missouri. Investigators evaluated barriers to mammography screening as part of an outreach registry of Breast Health Center patients to determine the effectiveness of mobile mammography among the medically underserved (Abstract 13).1

They surveyed 8739 women, the majority of whom were black (54%), were uninsured (74%), and had an annual income <$20,000 (87%). Three major barriers to mammography screen­ing among this underserved population were identified: fear of cost (40%), fear of mammogram-related pain (13%), and fear of receiving bad news (13%). Compared with white patients, non-Hispanic African Amer­icans were 2 times as likely and Hispanics were 3 times as likely to report being afraid of receiving bad news.

Mammography was most rare among patients living in the Missouri Bootheel geographic area, those without insurance, those from ethnic and racial minority backgrounds, and those who use only mobile mammography services. More breast health education is needed in these populations, the study concluded.

Sexual Dysfunction in Breast Cancer Survivors
Patient-perceived sexual dysfunction is a documented consequence of breast cancer treatment that patients feel is not being addressed effectively during routine care, according to the results of a 30-item survey of 75 postsurgical breast cancer patients conducted by Michigan State University researchers (Abstract 67).2

Sixty-four percent of women felt that their cancer treatment had a negative impact on sexual function, and 47% experienced emotional distress because of it. Although 60% expressed a desire to discuss the problem with a physician, only 23% did so. Nearly half of the respondents would like an appointment with a “counselor.”

Factors that interfered with sexual function were fatigue (76%), dyspareunia (65%), scars (57%), hot flashes (75%), and breast tenderness (75%). Whereas 42% of lumpectomy patients felt that their surgery had a negative impact on intimate relationships, this figure rose to 70% among mastectomy pa­tients. Interestingly, no significant dif­ference was observed between wom­en who had reconstruction versus those who did not. Sexual dysfunction was independent of age, postoperative interval, and interfering factors.

The authors encouraged providers to address issues of sexual dysfunction during follow-up and to intervene when appropriate.

Vascular Toxicities Do Not Lead to Endocrine Therapy Discontinuations
A large retrospective cohort study of 629 postmenopausal women treated with endocrine therapy found a high incidence of vascular toxicities, but a low rate of treatment discontinuations because of this (Abstract 68).3 The vascular toxicities were consis-­tent with those described in published reports: with aromatase inhibitors, an increase in cardiovascular events and hypercholesterolemia; and with tamoxifen, a higher incidence of thrombosis.

Vascular toxicities were observed in 37% of patients receiving tamoxifen and 25% to 35% of patients on aro­matase inhibitors. The most common toxicities seen with tamoxifen were peripheral edema (23.2%) and thromboembolic events (7.1%). Patients on aromatase in­hibitors were also likely to have peripheral edema (19%), as well as hypercholesterolemia (5.4%), ar­rhy­thmia (5.2%), and cardiovascu-lar events (4.8%). Pre­existing vascular comorbidities significantly increased the risk of developing a new vascular toxicity if the patients were taking letrozole or tamoxifen.

Treatment was discontinued due to vascular toxicity 3 times more often with tamoxifen (11%) than with an aromatase inhibitor (3%), mostly due to thromboembolic events (7.1% vs 2.9%).

“These results are encouraging and suggest that the risk of vascular toxicities should not preclude selection of the optimal endocrine strategy,” said Susan F. Dent, MD, of the Ottawa Hospital Cancer Centre in Canada.

Metformin May Reduce Risk of Developing Breast Cancer
A meta-analysis of published studies found that metformin use in women with diabetes is associated with a 17% lower risk of developing invasive breast cancer (Abstract 25).4 The analysis id­en­t­ified 443 studies, of which 7 (all ob­servational) met study criteria. Dia­betic women taking metformin experienced an overall 17% reduction in the risk of breast cancer. The risk reduction was 25% for those taking the drug for more than 3 years, and 6% when exposure was 3 years or less. Older studies (prior to 1997) also found a greater association.

“Because this finding is based upon observational studies, it may reflect bias or confounding,” acknowledged Rowan T. Chlebowski, MD, PhD, of the David Geffen School of Medicine at the Uni­versity of California Los Angeles. “But the finding of a stronger effect size associated with studies of longer duration of metformin use and those that had longer observation periods suggest that the finding may be real. If the result is confirmed in prospective studies with a large number of breast cancer events, clinical trials should assess whether metformin can reduce breast cancer risk.”

Statin Use Ameliorates Risk of Bone Metastasis
The use of statins was associated with a reduced risk of bone metastases in breast cancer and improved disease-free survival (Abstract 40).5 The study, by investigators from Albert Einstein Medical Center in Philadelphia, Penn­sylvania, was a retrospective review of 841 stage I to III breast cancer patients, stratified according to the use of statins for 3 months or longer. Patients who used statins had a 51% reduction in metastasis to the bone, but not to other sites. Their median disease-free surviv­al was 63.6 months versus 53.9 months among nonusers.

Gentry T. King, MD, explained that the mevalonic acid pathway has been implicated in the promotion of a microenvironment for bony metastasis from breast cancer. The statins, which act on this pathway, have in vitro antineoplastic and antiosteoclast activity against breast cancer through interference with this pathway.

“I would not yet prescribe a statin for the purpose of reducing bone metastasis risk,” he said, “but if patients are already on them, because of the possible protective effect, I would certainly not take the patient off the statin.”

References

  1. Fayanju OM, Kraenzle S, Drake BF, et al. Barriers to mammography among underserved women in a breast health center outreach program. Presented at: Amer­ican Society of Clinical Oncology 2012 Breast Cancer Symposium; September 13-15, 2012; San Francisco, CA. Abstract 13.
  2. Block EA, Zomerlei TA, Keto J, et al. Perceived sexual dysfunction in breast cancer survivors. Presented at: American Society of Clinical Oncology 2012 Breast Cancer Symposium; September 13-15, 2012; San Francisco, CA. Abstract 67.
  3. Dent SF, Crawley FL, Graham NA, et al. Vascular toxicities of endocrine therapy in early-stage breast cancer: encouraging observations in a nontribal setting. Presented at: American Society of Clinical Oncology 2012 Breast Cancer Symposium; September 13-15, 2012; San Francisco, CA. Abstract 68.
  4. Col N, Ochs L, Springmann V, et al. Metformin and breast cancer risk: a meta-analysis and critical literature review. Presented at: American Society of Clinical Oncology 2012 Breast Cancer Symposium; September 13-15, 2012; San Francisco, CA. Abstract 25.
  5. King GT, Yun JH, Chae YK, et al. Statin use and the development of bone metastasis in breast cancer patients. Presented at: American Society of Clinical Oncology 2012 Breast Cancer Symposium; September 13-15, 2012; San Francisco, CA. Abstract 40.
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Last modified: May 21, 2015