The link between oral contraceptives and ovarian cancer mortality rates

The link between oral contraceptives and ovarian cancer mortality rates
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Death rates from ovarian cancer are predicted to fall in 2022 in the UK and EU countries and the growing use of oral contraceptives could explain why.

Researchers uncovered that predicted ovarian cancer death rates are expected to fall by 17% in 2022 in the UK and by 7% in EU countries in 2022 compared to 2017. The team, led by Carlo La Vecchia (MD), a professor at the University of Milan (Italy), said that these dramatic falls are due mainly to the use of oral contraceptives, which also account for the differences between countries.

“The earlier and greater use of oral contraceptives in the UK than in most EU countries for generations of women born since the 1930s has a major role in these trends,” said Professor La Vecchia. “In Italy, Spain, Poland etc., oral contraceptives were made available considerably later, and hence the favourable trends in these countries started later and are smaller.”

The new research has been published in the leading cancer journal Annals of Oncology.

The rise of oral contraceptives

The researchers predict that 26,500 women will die from ovarian cancer in EU countries in 2022 and 4,000 in the UK. After adjusting for differences in age distribution in the population, the age-standardised rate (ASR) of deaths will be 4.32 and 4.57 women per 100,000 in the EU and UK, respectively. In the 1970s, the UK had the highest death rate in Europe at nearly nine per 100,000 but then showed a steep decline. Whereas death rates in France, Germany, Italy, Poland and Spain were all lower but showed a rise until the 1980s when they started to decline except for Poland, where rates continued to rise until around 2010.

“Long-term use of oral contraceptives reduces the risk of ovarian cancer by 40% in middle-aged and elderly women,” said Professor La Vecchia. “Other factors may also be partially responsible, such as reduced use of hormone replacement therapy. Improvements in diagnosis, surgery and the use of better treatments, such as platinum-based drugs in the 1980s, taxanes in the 1990s and more recently, gemcitabine, intraperitoneal chemotherapy, possibly bevacizumab, and PARP inhibitors for women with BRCA mutations, may all contribute to improved survival. However, these factors are minor compared to the long-term protective effect of oral contraceptives. We expect these favourable trends in ovarian cancer deaths to continue.”

In the UK, there are currently three main types of oral contraceptives including, Monophasic 21-day pills, Phasic 21-day pills and Every day (ED) pills.  The Monophasic 21-day oral contraceptive pill is the most common type, one pill is taken each day for 21 days, followed by a seven-day break. Oral contraceptives aim to stop the sperm from reaching the egg; therefore, pregnancy cannot occur.

Cancer death rates will continue to fall

Professor La Vecchia and his colleagues predict that death rates from the ten most common will continue to fall in most European countries in 2022, although the numbers of people dying will go up due to ageing populations. A greater proportion of elderly people in the population means there is a greater number at the age where they are more likely to develop and die from cancer.

There will be 1,446,000 deaths from cancer in the EU and the UK in 2022 (1,269,200 in the EU and 176,800 in the UK). This corresponds to a fall of 6% in men (126.9 deaths per 100,000) and 4% in women (80.2 per 100,000) in the EU since 2017, and 7% (113.2 per 100,000) in men and 6% (87.6 per 100,000) in women in the UK.

Death rates continue to rise for pancreatic cancer; rates have increased in women (up 3.4%) with little change in men (down 0.7%) in the EU. However, in the UK, they are down 5% in men and 2% in women. It has overtaken breast cancer to become the third most common cause of cancer death in the EU (87,300 deaths, with a death rate of 8.1 and 5.9 per 100,000 in men and women, respectively). Furthermore, lung cancer deaths continue to rise in EU women (up 2%), although the rate of increase is slowing, and womb and cervical cancer deaths are up 5% in UK women.

Professor La Vecchia said: “Tobacco continues to play a key role and is the major cause of deaths from cancer across Europe. Smoking influences death rates from a range of cancers, including pancreatic, lung and bladder cancers. The lack of progress on pancreatic cancer should ring alarm bells with EU health institutions as survival rates are abysmal with less than 5% of patients surviving five years.”

Co-author, Professor Eva Negri, professor at the University of Bologna (Italy), said: “Besides the decline in smoking prevalence in men, the main determinants of the favourable trends in cancer mortality are advancements in treatment and diagnosis of colorectal, breast and prostate cancer, as well as in several rarer cancers.”

Insight into the UK and EU

The researchers analysed cancer death rates in the EU 27 Member States as a whole and separately in the UK to compare with previous years where the UK was a member of the EU. Additionally, they analysed the five most populous EU countries (France, Germany, Italy, Poland, and Spain) and, individually, for stomach, intestines, pancreas, lung, breast, uterus (including the cervix), ovary, prostate, bladder and leukaemias for men and women. Professor La Vecchia and his colleagues collected data on deaths from the World Health Organization and Eurostat databases from 1970 to 2017, or to 2016 for the UK. This is the twelfth consecutive year the researchers have published these predictions. Professor La Vecchia and his team are the only group in Europe to publish yearly predictions for all cancers, as well as the ten most common cancers.

They estimate that nearly 5.4 million cancer deaths have been avoided between 1989 and 2022 in the EU, 369,000 in 2022 alone, compared to the peak of cancer death rates in 1988. In the UK, just over a million deaths were avoided over the same period, including 73,000 in 2022.

The researchers warned that their predictions should be interpreted with caution and that they could be affected by the COVID-19 pandemic this year.

Co-author, Professor Paolo Boffetta (MD), Annals of Oncology associate editor for epidemiology, professor and associate director for population sciences at Stony Brook University, New York (USA), and professor at the University of Bologna (Italy), said: “The COVID-19 epidemic can indeed affect the positive trends in cancer mortality that have been observed over the last decade in Europe. We expect that the vaccination campaign that has targeted oncology patients as a priority population will mitigate the adverse impact that has been observed during 2020, even if these patients have a weaker immune response compared to healthy individuals.”


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