This is the latest post in a bi-monthly series looking at several of the most interesting cancer research stories that have come out over the previous two months. These are a few of the recent stories that seem to have the greatest potential impact, at least from my perspective, and that I know I’ll want to follow as they develop further.
Below are overviews of several top cancer research stories that came out in January and February 2014, including studies on mammography, risk reduction for carriers of BRCA gene mutations and radiation therapy for early stage breast cancer.
1) Mammography: a 25-year randomized, controlled trial in Canada found that the addition of mammography to screening with physical breast exams did not reduce deaths from breast cancer.
This study, published in the British Medical Journal, is one of the largest and longest-running clinical trials of mammography conducted. It included about 90,000 women between the ages of 40 and 59. Women in their fifties were randomized to receive annual mammograms along with physical breast exams or to receive annual breast exams only. Women who were in their forties were randomized to receive annual mammograms and breast exams or to just receive an initial breast exam followed by normal medical care in their communities.
These were the study’s main findings:
- The number of deaths from breast cancer over the 25-year period was about the same for the women receiving mammography and those not receiving mammography. These results did not differ by age group (women in their forties and women in their fifties).
- The addition of mammography to clinical breast exams and usual care does not reduce deaths from breast cancer when access to care is freely available for any who are diagnosed with breast cancer.
- Mammography screening led to a greater number of breast cancer diagnoses but about 22% of these, or 1 for every 424 women who received mammography screening in the trial, were cases that would never have become life-threatening.
Numerous articles and commentaries on the study have appeared over the last few weeks. Here are a few that I found helpful for insights on the implications of the study.
- Gayle Sulik and Bonnie Spanier of Breast Cancer Consortium explain that the study adds new information to what is known about the benefits and harms associated with this type of screening by showing the extent to which mammography, when compared with physical breast exams, contributes to overdiagnosis and overtreatment.
- There have been criticisms of the design and quality of the study such as this from the American College of Radiology. Others, such as Jennifer Gunter, MD, an obstetrician-gynecologist and contributor to the blog Kevin MD, have commented on the validity of these criticisms.
- Otis Brawley, MD, chief medical officer of the American Cancer Society and an expert in cancer screening, evaluates the implications of the study’s findings in light of both the existing body of knowledge from breast cancer screening trials as well as current recommendations on mammography screening from various organizations.
2) Risk Reduction: for women who are carriers of the BRCA1 and BRCA2 gene mutations, a study confirmed that removal of the ovaries reduces the risk of ovarian cancer by 80% and also considered the optimal age for the surgery
A new study involving about 6,000 women reaffirmed the longstanding recognition that removal of the ovaries, or oopherectomy, substantially reduces the risk of ovarian cancer and also reduces the risk of breast cancer for BRCA1 and BRCA2 mutation carriers. The findings were published in the Journal of Clinical Oncology on February 25, 2014. As reported in Medical Express, the study found oopherectomy was associated with a 80% reduction in ovarian cancer risk, a 77% reduction in the risk of death from all causes and a 68% lower risk of death from all causes in women who previously had breast cancer.
In addition, as reported in a number of articles, the study’s authors state that the findings suggest BRCA1 mutation carriers should consider oopherectomy by age 35, while BRCA2 mutation carriers can safely wait until age 40 because their risk of ovarian cancer is not as great. But for younger women, there are significant side effects and quality of life issues associated with the surgery. For further discussion of the study and what it may mean for BRCA1/2 carriers, see this article by Liz Szabo in USA Today and this piece by Lauran Neergaard in Huffington Post.
3) Radiation Therapy: Two recent studies evaluated the use of brachytherapy in treatment for early stage breast cancer
Radiation therapy is often used following breast conserving surgery for early stage breast cancer to reduce the risk that cancer will come back in the breast or nearby lymph nodes. Standard external beam radiation is given 5 days a week over several weeks, but newer forms of radiation allow for more concentrated doses of radiation to be given over a shorter time frame. One of these approaches is brachytherapy, also known as internal radiation. Brachytherapy delivers radiation through radioactive seeds or pellets placed into the breast tissue next to the cancer. (Source: American Cancer Society)
Several ongoing clinical trials are comparing brachytherapy to standard external beam radiation. Pending results of those trials, two recent studies analyzed outcomes associated with brachytherapy.
One study looked at a cohort of 157 women receiving treatment with brachytherapy at a single facility in Pittsburgh, Pennsylvania from 2002 to 2007. The women’s health outcomes were studied for a period of five years following treatment. The study found that this group of patients had very low recurrence rates, good cosmetic outcomes and minimal late toxicity.
Another recent study looked at data for about 36,000 women who were 66 years old or older, diagnosed with early stage breast cancer between 2002 and 2207, and treated with either brachytherapy or standard external beam radiation. Through five years of follow-up after treatment, all of the women did well, but this study found that of these older women, those that were at higher risk of recurrence did better with standard external beam radiation.
The U.S. Preventative Services Task Force issued a recommendation stating that it found “inadequate evidence on the benefits of supplementation with multivitamins to reduce the risk for cardiovascular disease or cancer.” As discussed in this article in Time, doctors are starting to advise patients who don’t have a known deficiency to stop taking multivitamin supplements.
In an article in Nature, Francis S. Collins and Lawrence T. Tabak discuss the problem that published preclinical research findings are often not able to be reproduced by other scientists and describe initiatives that the National Institutes of Health is undertaking to address this problem.
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