Women survive more than men to different types of cancer

To know the impact or magnitude of cancer in a given population, 3 epidemiological indicators are used: 1) mortality (deaths), which translates the lethality of the disease, 2) incidence (new cases), which expresses the risk of developing a cancer, and 3) survival, which reflects the natural history of the disease and the effectiveness of treatment.

This information is very useful for the surveillance and control of cancer in the population.

According to the latest incidence data, provided by the Spanish Network of Cancer Registries (REDECAN), in 2022, 120.000 new cases of cancer in women will be diagnosed in Spain, which represents a slight increase compared to previous years, although this estimate does not take into account the possible effect of the Covid-19 pandemic on the decrease in diagnosed cases.

The most frequent cancers diagnosed in women in Spain in 2022 will be those of the breast and those of the colon and rectum. At a great distance, it is followed in frequency by those of the lung, uterine body, thyroid, pancreas and urinary bladder.

We have recently published an article in the journal Cancers with data from 13 cancer registries covering 30% of the Spanish population, with 421.000 new cases of cancer diagnosed in adults between 2002 and 2013.

Of the 23 types of cancer studied, survival 5 years after diagnosis was higher in women than in men, overall and for 9 types (cancer of the oral cavity and pharynx, thyroid cancer, cutaneous melanoma, multiple myeloma, cervical cancer). lung, stomach and pancreatic cancers, non-Hodgkin's lymphoma and acute myeloid leukemia). For the rest of the cancers, survival was similar in men and women.

For all cancers, survival in men was 7 points lower than in women (55% and 62%, in men and women, respectively). On the other hand, 57% of women with cancers of the oral cavity and pharynx survived 5 years after diagnosis, while in the case of men only 38% did, almost 20 points less.

Lung cancer deserves a specific comment. There is a different pattern of incidence trends in both sexes, such that, in the last decade, the number of new cases of lung cancer in women has increased substantially, while cases in men have decreased, although lung cancer is five times more frequent in them. For this cancer, fundamentally related to tobacco consumption, differences are also observed in survival at 5 years, being 13% in men and 18% in women, 5 points more.

In addition, it is important to point out an increase in survival, for all the cancers studied, between the two periods studied (2002-2007 and 2008-2013), which it may be reflecting: 1) a diagnosis of cancer cases in earlier stages, 2) advances in the approach to cancer, and 3) greater effectiveness of treatments. Thus, for example, much of the increased survival for various hematological malignancies is probably due to therapeutic advances, a consequence of greater use of more effective treatments and better stratification of patient groups due to advances in cytogenetics and biology. molecular. However, in some cancers, at least part of the improvement in survival may be due to increased diagnosis of cases with a good prognosis, as may have occurred with thyroid and kidney cancer.

In general, cancer survival decreases with increasing age and stage at diagnosis, in both men and women. Therefore, cancers with more advanced stages at diagnosis have worse survival figures.

These data are crucial indicators to evaluate the Cancer Strategies of Health Systems and the effectiveness of health services for cancer patients. Survival is highly influenced, in addition to the aggressiveness of the cancer, by the stage of the disease at diagnosis (early or advanced) and the effectiveness of treatments.

Possible explanations for these differences in cancer survival between men and women include a biological advantage mediated by women's sex hormones. We cannot ignore other differences in the anatomical sublocations of the tumors and different histological types, as well as the differences in the prevalence of risk factors between both sexes (tobacco and alcohol consumption), associated diseases (comorbidities) and socio-economic factors. cultural factors that might favor earlier diagnosis in women.

It is essential that we continue to study the reason for this gender gap and these differences in cancer survival between men and women, including additional data on the stage of the tumor at the time of diagnosis, as well as other potential explanatory factors, such as aggressiveness of the tumor, to better understand the differences by sex and identify possible actions to reduce them.

And finally, the role of population cancer registries must be strengthened, as fundamental tools to continue monitoring and exhaustively controlling cancer survival in the Spanish population.

Dr. Maria José Sánchez Pérez. Professor at the Andalusian School of Public Health. Scientific Director of the Biosanitary Research Institute of Granada (ibs.GRANADA)