Overweight and obese women at greater risk of breast cancer recurrence
Women who are overweight or obese when they are diagnosed with breast cancer are at higher risk of cancer recurrence or related death than are leaner women, according to a new study to be presented to the 8th European Breast Cancer Conference (EBCC-8) today (Friday). This finding held true even though the study mandated that chemotherapy dosage be adjusted for body weight, and adds further to the evidence that lifestyle factors can influence cancer prognosis, a researcher will tell the conference.
Dr. Jennifer Ligibel, a medical oncologist at the Dana-Farber Cancer Institute, Boston, USA, and an Associate Professor at Harvard Medical School, and colleagues, studied data from 1909 patients who were enrolled into a study called CALGB 9741 between 1997 and 1999. The study was set up to investigate different dosing schedules for adjuvant chemotherapy in patients where cancer cells were found in the lymph nodes (node-positive cancer). The presence of such cells in the lymph nodes means that there is a higher chance of cancer returning after surgery.
After extracting height and weight data from the patient records, they went on to evaluate the relationship between body mass index (BMI) with relapse-free survival (RFS) and overall survival (OS). 1.2% of the patients were underweight, 32.6% normal weight, 32.9% overweight, and 33.3% obese. 49% of patients were menopausal, 65% had oestrogen-receptor positive cancers, where the presence of oestrogen encourages the tumour to grow, and 70% received the oestrogen-receptor blocking treatment, tamoxifen.
“Several other studies have shown that being overweight or obese at the time that a woman is diagnosed with breast cancer is linked to a higher risk of recurrence. However, questions have been raised in the past whether obese women were receiving relatively lower doses of chemotherapy due to their weight. Our study mandated that each patient received a chemotherapy dose adjusted to her weight, so these results suggest that treatment factors are not responsible for the differences in recurrence rates seen in heavier women,” Dr. Ligibel will say. “We found that BMI was related to both RFS and OS; for example, the ten-year RFS of a patient who was overweight was 70%; compared with 65% for one who was obese.”
Although the link between obesity and the development of breast cancer is well known, there has been less research to date looking at its effect on cancer recurrence and survival.
How Do I Know There Is A Recurrence of Breast Cancer?
If you’ve been treated for breast cancer, you should continue to practice breast self-exam, checking both the treated area and your other breast each month. You should report any changes to your doctor right away. Breast changes that might indicate a recurrence include:
- An area that is distinctly different from any other area on either breast.
- Lump or thickening in or near the breast or in the underarm that persists through the menstrual cycle.
- A change in the size, shape, or contour of the breast.
- A mass or lump, which may feel as small as a pea.
- A marble-like area under the skin.
- A change in the feel or appearance of the skin on the breast or nipple, including skin that is dimpled, puckered, scaly, or inflamed (red, warm, or swollen)
- Bloody or clear fluid discharge from the nipples
- Redness of the skin on the breast or nipple
In addition to performing monthly breast self-exams, keep your scheduled follow-up appointments with your doctor. During these appointments, your health care provider will perform a breast exam, order lab or imaging tests as needed, and ask you about any symptoms you might have. Initially, these follow-up appointments may be scheduled every three to four months. The longer you are cancer-free, the less often you will need to see your doctor. Continue to follow recommendations on screening mammograms (usually recommended once a year).
“When you consider that data from 2007-8 [1] show that 68% of US adults aged 20 years and over were overweight or obese, as compared to only 56% of the same group in 1998-1994, you can see the way the problem is growing. That is why we think it is a matter of urgency to find out as much about the relationship between obesity and cancer as we can,” Dr. Ligibel will say.
The researchers intend to follow up their work by learning more about how weight-related factors could influence breast cancer outcomes. A number of studies currently underway are looking at how changing lifestyle behaviours, for example losing weight, exercising more, and eating a better diet, affects the hormones in women’s bodies that have been linked with breast cancer. Ultimately, they say, they are interested in studying the impact of deliberate weight loss on the risk of recurrence in women with early breast cancer.
About 1 in 5 breast cancer survivors who have completed 5 years of adjuvant therapy suffer a recurrence within the 10 years after their treatment, according to a recent study in the Journal of the National Cancer Institute.
The study offers women a detailed picture of how likely they are to face a recurrence further down the road.
Abeena Brewster, MD, and colleagues at the M.D. Anderson Cancer Center in Houston, Texas looked at the risk of recurrence in nearly 3,000 women with stage I, II, and III breast cancer who were treated at the center from 1985 through 2001. All of the women had neoadjuvant or adjuvant chemotherapy or hormonal therapy.
For the overall group, recurrence rates were 11% at 5 years and 20% at 10 years after completion of adjuvant therapy.
Brewster and colleagues reported that recurrence risk increased with higher stage. Five-year recurrence rates were 7%, 11%, and 13% for women with stages I, II, and II disease, respectively.
Recurrence rates also varied by grade, which is a description of how the breast cancer cells look under a microscope. Breast cancer cells are graded on a scale from 1 to 3 – the higher the grade, the more abnormal the cells look and more likely they are to grow quickly. Five-year recurrence rates for women with grades 1, 2, and 3 tumors were 14%, 13%, and 9%, respectively.
The risk of recurrence seemed to be affected by the hormone receptor status of the cancers, as well. The 5-year recurrence rate was 7% for women with hormone receptor-negative tumors and 13% for those with hormone receptor-positive disease.