Worldwide breast cancer incidence increased by more than 25% since 1980

Global analysis estimates there were 2 million new cases of breast and cervical cancer in 2010.

An analysis of cancer registry data collected in 187 countries showed that more women in both developed and developing countries were increasingly likely to be diagnosed with breast cancer and to die of the disease.

Conversely, worldwide incidence of cervical cancer and cervical cancer mortality did not increase as rapidly. However, women in the developing world were at greater risk for incidence and death in both diseases.

Jonathan S. Berek, MD, MMS, chair of obstetrics and gynecology at Stanford University School of Medicine and director of the Stanford Women's Cancer Center at Stanford Cancer Institute, said the results in developing countries are symptomatic of a larger crisis in public health care.

"Death rates from maternal mortality, infectious disease, starvation and dehydration far exceed that of cancer," Berek said. "In many of these countries, cancer isn't even considered a high priority."

Researchers systematically collected cancer registry data on mortality and incidence, vital registration and verbal autopsy data from 1980 to 2010. They supplemented vital registration and verbal autopsy with incidence multiplied by the mortality-to-incidence ratio to yield a comprehensive database of mortality rates. Data on patients in 47 countries, mostly in sub-Saharan Africa, were unobtainable.

Collection methods varied by country, and some data are likely more reliable than others. Berek noted the difficulty in collecting and interpreting the statistics in this study; the researchers, alternatively, said cervical cancer incidence increased by an annual average 0.6% during the study period and cumulative global incidence of cervical cancer decreased during the study period.

"The value here is that we learn trends," Berek said. "If we could develop a way of intervening, we can track numbers. However imperfect, we know that there the intervention is probably taking hold. There is also a value in understanding globally how bad the problem is."

From 1980 to 2010, the overall number of breast cancer diagnoses has more than doubled from 641,000 to 1.64 million, an annual increase of 3.1%. More than two-thirds of women diagnosed with breast cancer in 2010 were aged 50 years and older, and 39% of those women lived in developed countries.

More than 75% of cervical cancer diagnoses occur in the developing world, and 17% of those cases occurred in sub-Saharan Africa in 2010. Additionally, incidence has been increasing in the developing world, even as the number of diagnoses in wealthier nations remains constant.

For women aged 15 to 49 years, there were more than twice as many women in developing countries diagnosed with breast cancer, 23% vs. 10%. Younger women in developing countries represented 367,000 cases of breast cancer in 2010. Nearly 45% of the diagnoses of cervical cancer in the developing world are in women aged 15 to 49 years.

"It may not be that the younger demographic is getting cervical cancer more often so much as we're finding it sooner. That's a little hard to ascertain, but if you correct for stage, there seems to be some evidence for that," Berek said. "In breast cancer, I'm not sure what the answer is. There may be some stage-shifting there, as well. Part of this may be detection bias; I don't know that we're seeing a biologic phenomenon."

Worldwide cumulative probability was 5.6% for breast cancer and 1.4% for cervical cancer in 2010. Cumulative probability for developing either disease remained higher for women in developed countries.

However, women in the developing world died of breast cancer in far greater numbers in 2010 (213,700 vs. 211,400), even though women in the developed world were nearly twice as likely to die of the disease (1.3% vs. 2.4%).

An estimated 155,000 women in the developing world died of cervical cancer in 2010 compared with 44,700 in the developed world. Cumulative incidence for death was also higher in the developing world, 0.8% vs. 0.5%. - by Jason Harris

For more information:

Forouzanfar MH. Lancet. 2011;doi:10.1016/S0140-6736(11)61351-2 .

Earn CME this spring at the HemOnc Today Breast Cancer Review & Perspective meeting to be held March 23-24, 2012 at the Hilton San Diego Bayfront. See details at HemOncTodayBreastCancer.com.

Follow HemOncToday.com on Twitter.