Obesity, alcohol consumption, and smoking significantly increase the risk of second breast cancers among breast cancer survivors, according to the results of a study published in the Journal of Clinical Oncology.1
Approximately 200,000 women are diagnosed with breast cancer every year in the United States alone. Treatment for the disease has improved, and five-year survival rates are now greater than 90 percent; however, survivors have a significantly increased risk of developing a second breast cancer in the opposite breast.2
Researchers from the Fred Hutchinson Cancer Research Center in Seattle conducted a study that involved 365 women who were diagnosed with an estrogen receptor–positive (ER-positive) first primary breast cancer and then later diagnosed with a second primary breast cancer. These women were compared with 726 matched controls who were diagnosed with only an ER-positive primary breast cancer.
The researchers reviewed medical records and conducted patient interviews to ascertain data on obesity, alcohol consumption, and smoking. The results indicated that women who were considered obese (body mass index [BMI] over 30 kg/m2) were 50 percent more likely to develop a second breast cancer than women who had a BMI lower than 25 kg/m2. Furthermore, women who consumed more than seven drinks per week after their first breast cancer diagnosis had a 70 percent higher risk of developing a second breast cancer compared with nondrinkers. Finally, women who smoked were more than twice as likely to develop a second breast cancer compared with nonsmokers.
The researchers concluded that lifestyle factors such as obesity, smoking, and drinking could significantly increase the risk of developing a second cancer. Modifying these factors might provide breast cancer survivors with a way to reduce their risk of developing a second cancer.
1. Li CI, Daling JR, Porter PL, Tang MT, Malone KE. Relationship between potentially modifiable lifestyle factors and risk of second primary contralateral breast cancer among women diagnosed with estrogen receptor–positive invasive breast cancer. Journal of Clinical Oncology [early online publication]. September 8, 2009.
2. Chen Y, Thompson W, Semenciw R, Mao Y. Epidemiology of contralateral breast cancer. Cancer Epidemiology, Biomarkers, and Prevention. 1999;8(10):855-61.
Number of Obesity-related Cancers Is Growing
In 2008 excess body weight was responsible for more than 124,000 new cancer diagnoses in Europe. These results were presented at a major European cancer conference.
Obesity is increasingly being recognized as a risk factor not only for cancer development but also for worse outcomes after cancer treatment. Links between obesity and endometrial cancer, postmenopausal breast cancer, and colorectal cancer are well established, but the effects of obesity appear to extend to several other types of cancer as well. According to the results of a large study conducted by the American Cancer Society, women with the highest body mass index (BMI) numbers were more likely than women with a healthy BMI to die of cancers of the gallbladder, pancreas, kidney, cervix, and ovary as well as non-Hodgkin’s lymphoma. The researchers estimated that 90,000 cancer deaths per year could be prevented if Americans maintained a healthy weight.1
BMI is a common (though imperfect) measure of body size. It involves a comparison of weight to height (weight in kilograms divided by height in meters squared, or kg/m2). A BMI between 18.5 kg/m2 and 24.9 kg/m2 is generally considered healthy, a BMI between 25 kg/m2 and 29.9 kg/m2 is considered overweight, and a BMI of 30 kg/m2 or higher is considered obese.
To explore the impact of excess body weight on cancer trends in Europe, researchers collected information from a number of different sources, including the World Health Organization and the International Agency for Research on Cancer.2 Excess body weight was defined a BMI of 25 kg/m2 or higher.
In 2002 an estimated 70,000 cancer diagnoses in Europe were due to excess body weight.
By 2008 this number was projected to be more than 124,000. Excess body weight accounted for 3.2 percent of all new cancer diagnoses in men and 8.6 percent of all new cancer diagnoses in women. Endometrial (uterine) cancer, postmenopausal breast cancer, and colorectal cancer were the most common weight-related cancers. These three cancer types accounted for 65 percent of all cancers due to excess body weight.The researchers note that these estimates are conservative and that the actual number of obesity-related cancers is likely to be higher.
According to Andrew Renehan, PhD, FRCS, FDS, the lead author of the study, “As more people stop smoking and fewer women take hormone replacement therapy, it is possible that obesity may become the biggest attributable cause of cancer in women within the next decade.”
References 1. Calle EE, Rodriguez C, Walker-Thurmond K, Thun MJ. Overweight, obesity, and mortality from cancer in a prospectively studied cohort of U.S. adult. New England Journal of Medicine. 2003;348(17):1625-38.
2. Renehan A. Obesity and overall cancer risk. Paper presented at: Joint ECCO 15–34th ESMO Multidisciplinary Congress; September 20–24, 2009; Berlin, Germany. Abstract I-327.
Study Explores Over diagnosis of Prostate Cancer
For every man who benefits from prostate cancer screening, many more are diagnosed and treated unnecessarily. The extent of this “overdiagnosis” of prostate cancer was explored in a study published in the Journal of the National Cancer Institute.
Each year in the United States, more than 192,000 men are diagnosed with prostate cancer and more than 27,000 die of the disease.
Men 50 years of age or older in the United States are often offered prostate-specific antigen (PSA) testing for the early detection of prostate cancer. The test may be offered at a younger age to men at high risk of prostate cancer. The PSA test measures proteins that are produced and shed by the prostate. PSA levels tend to be elevated when prostate cancer is present, but levels can also be elevated in benign (non-cancerous) conditions affecting the prostate.
A concern with the use of PSA testing is that it may identify some cancers that do not require treatment. This is sometimes referred to as “overdiagnosis.” Research suggests that some prostate cancers are very slow growing and will not affect a man’s health during his lifetime. Diagnosis and treatment of these cancers exposes men to the complications of cancer treatment without providing a benefit.
To explore how frequently overdiagnosis has occurred since PSA screening became widespread in the United States, researchers evaluated information from a large, national cancer registry. They assessed prostate cancer trends from 1986 (the year before an influential PSA study was published) to 2005.
During the 30 years since the introduction of PSA testing, PSA testing has resulted in 1.3 million more prostate cancer diagnoses than would have occurred otherwise. Roughly 1 million of these men received treatment for prostate cancer.
The increase in prostate cancer diagnoses after the introduction of PSA testing was most apparent in younger men. Prostate cancer incidence rates have tripled in men in their fifties and increased by more than sevenfold in men younger than 50.
There has been a decline in prostate cancer mortality during the PSA screening era, but it’s unclear how much of this decline is due to screening (improvements in treatment are likely to have also played a role). Nevertheless, even if all the decline in mortality is due to screening, the results of this study suggest that relatively few men have benefited from early detection.
This study highlights the importance of an informed decision-making process about prostate cancer screening, in which men who are considering being screened fully understand what is known about the potential risks and benefits.
References Welch HG, Albertsen PC. Prostate cancer diagnosis and treatment after the introduction of prostate-specific antigen screening: 1986–2005. Journal of the National Cancer Institute [early online publication]. August 31, 2009.
Tags: Cancer Prevention