Women diagnosed with invasive breast cancer are 39% more likely to develop a second cancer in a different part of the body. Such is the conclusion of a recent study, pioneered by female Spanish researchers. The study suggests that this increased risk could be due to the similar risk factors involved in both cancers, or to the side effects of the treatment received by breast cáncer patients.
A national team of researchers has analysed the risk that women diagnosed with a first case of invasive breast cancer face of developing a second primary cancer in a part of the body other than the breast.
The results, published in the journal Gynecologic Oncology, indicate that this risk is 39% higher. María José Sánchez, co-author of the study and director of the Granada Cancer Register explained to SINC that the team's study is the first populational study ever conducted in Spain to examine this associated risk.
According to the study's data, women under the age of 50 who had previously suffered from breast cancer were almost twice as likely to develop a second cancer than the general population (the risk was 96% greater). In women over the age of 50, a second cancer was 29% more likely. In the latter age group, the risk of developing an endometrial cancer was three times higher if breast cancer had been previously diagnosed.
The risk of developing a second ovarian cancer was found to be almost five times higher among young women diagnosed with a breast tumour than it was among the general population. Both age groups were found to be at greater risk of later developing a non-melanoma skin cancer.
Sánchez affirms that the risk of developing a second cancer was high in the first five years following the first diagnosis of breast cancer, and almost 3.5 times higher than that faced by other women. However, the researcher states that more than five years after this first diagnosis, the risk of developing a second cancer was not significantly higher than that of those unaffected by the disease.
The authors of the study examined a total of 5,897 cases of invasive breast cancer diagnosed between 1985 and 2007 in women resident in the province of Granada. In 314 of the cases, the women developed a second primary cancer..
The team studied a further 22,814 cases of cancer affecting all parts of the body except the breast, all of which were diagnosed in the same period and all as part of the same study population. Of these women, 171 developed a second cancer, this time of the breast.
Breast cancer: the state of play
Breast cancer continues to be one of the most frequently-occuring female cancers in developed countries. Despite the fact that the incidence of the disease has decreased slightly in the last decade, it remains high. This is due in part to the lifestyles adopted in the countries in question, which include a poor diet, a lack of exercise and obesity during the menopause.
The breast cancer survival rate has increased significantly in recent years.. According to data published in the Eurocare study, the relative survival rate at the five-year mark increased from 76% in the period 1990-1994 to 82.8% in the period 2000-2007.
According to Sánchez, the data produced by the study demonstrate that the number of women who survive breat cancer will continue to increase with time and that it is consequently necessary to evaluate the risk these women face of developing a second cancer in comparison with the general population..
This study was produced using data from the Granada Cancer Register, a population-based cancer register which covers a population of more than 900, 000 inhabitants (450, 000 women approx) and which was launched in 1985. In 2007, this register became part of the Andalucian Cancer Registry.
"European cancer registry based study on survival and care of cancer patients (Eurocare)".
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Molina-Montes, E. et al. Risk of second primary cancer among women with breast cancer: a population-based study in Granada (Spain), Gynecol Oncol. 2013;130(2):340-5. DOI: 10.1016/j.ygyno.2013.04.057