Post-Cancer Therapy and Survivorship Care
One of the reports that made international news was a study of more than 1,200 childhood cancer survivors. Researchers from MSKCC found that women who received radiation to the chest, as part of cancer therapy, during childhood may be at higher risk of breast cancer than others. These findings further reiterate the importance of preventing exposure to unnecessary therapies and toxicities. This report further highlighted the importance of survivorship care and research, as the effects of cancer treatment often linger long after therapy has ended.
Two primary issues facing survivors are lingering effects from cancer treatments and adherence to prevention therapy. The number one reason why patients stop treatment prematurely is the toxicity and residual effects associated with certain cancer treatments. Therefore, the discovery of biomarkers to help predict which patient will respond to or experience toxicity from a given therapy is crucial. Bryan P. Schneider, MD (Indiana University), known for his work in nerve damage associated with taxane-based chemotherapies called "neuropathy," reviewed five studies that examined patient outcomes and biomarker discoveries. Noting the additional research needed to be done before accurate biomarkers can be used in clinical practice, Dr. Schneider said, "Biomarkers are conventionally good at predicting which patients should be receiving therapy but bad at whom should not get a standard form of therapy." It is crucial to biomarkers that can prevent exposing patients to unnecessary toxicities.
Also, Debra L. Barton, PhD (Mayo Clinic, Rochester) reported that the plant ginseng appears to help relieve treatment-related fatigue in 90% of the 360 patients studied more than half of whom had breast cancer. Dr. Barton also explored the biological basis of why ginseng may have therapeutic benefits, namely in its inhibition of MAP kinase pathway and decreases HPA activation and pro-inflammatory cytokines. While the study results are promising, Dr. Barton cautioned that patients should use pure ground root of ginseng, as opposed to an extraction, which is sometimes processed with ethanol and can give the mixture estrogen-like properties that can actually stimulate the growth of ER+ breast cancer cells.
Dr. Barton in discussed several additional survivorship studies, including one led by Carol Fabian, MD (University of Kansas Medical Center) exploring the use of vitamin D to alleviate musculoskeletal pain. Many women undergoing aromatase inhibitor therapy report musculoskeletal pain, which causes them to stop taking the drugs prematurely. Study participants were randomized to receive different dosages of vitamin D or placebo along with letrozole, a form of AI. A significantly higher proportion of women on placebo experienced worsening of pain, disability, or fatigue than those on vitamin D. Therefore, researchers believe that there is merit in continuing to study vitamin D as a possible prevention agent against musculoskeletal pain for women on AIs.
Dr. Fabian also reviewed two studies on the controversial use of hormone replacement therapy (HRT) and its correlation to breast cancer incidence and mortality, as HRT has been associated with increased risk of developing breast cancer. Italian scientists looked at the concurrent use of HRT and tamoxifen as breast cancer prevention. Study results suggest that combining low-dose tamoxifen and HRT is safe and provides a promising way to retain the benefits while reducing the risks of either agent, even though additional studies are needed. On the other hand, further analyses based on the Women's Health Initiative data on over 41,000 post-menopausal women suggested that the use of estrogen plus progestin as HRT is associated with increased breast cancer incidence and mortality. Therefore, Dr. Fabian cautioned against the use of HRT including both estrogen and progestin in clinical practice.
A group of researchers including several BCRF grantees used the PAM50 assay, developed by Charles M. Perou, PhD (University of North Caroline, Chapel Hill), to evaluate breast cancer subtypes among a group of older patients and found that although more favorable subtypes increase with age, older breast cancer patients still have a substantial percentage of high-risk subtypes. Therefore, age alone was not a significant factor in outcome.
The issue of race and breast cancer subtypes was also examined. In one project, scientists looked whether people of different races have more of one breast cancer subtype than another. Based on results, it appeared that African American women tend to have fewer cases of luminal breast cancer, as reported in earlier studies.
Another issue in breast cancer treatment is the correlation with aging. Hyman Muss, MD (University of North Carolina, Chapel Hill, a pioneer in this field, reviewed data suggesting that elderly patients assessed to be in good general health can be given the same treatment as younger patients; however, older and frail patients may need adapted treatment or palliative therapy. Dr. Muss highlighted the need to consider life expectancy, potential for toxicity, co-morbidity, effects on function and quality of life, and patient preferences when working with older patients and recommended several widely available resources for assessing risk factors.