Various types of new large-scale research Hormone replacement therapy (HRT) is associated with increased risk breast cancer It provided additional information on the factors associated with that increased risk.
Research Published online On October 28th BMJ.
“This study confirms an increased risk of breast cancer in patients taking HRT, but shows that the magnitude of the risk depends on many factors,” said lead author Dr. Yana Vinogradova. Told. Medscape Medical News on mail. Vinogradava is a medical statistician at the University of Nottingham in the United Kingdom.
Studies also risk May be lower than estimated In a large meta-analysis of 24 trials Release In 2019 The lancet. In that study, researchers suggested that the risk of breast cancer from HRT was higher and lasted longer than expected.
This conclusion from the meta-analysis was widely reported in the general press and led to the publication by the UK Medicines and Healthcare Products Regulatory Agency. HRT safety warning Regarding breast cancer. Experts in this area questioned the warning, saying it caused excessive anxiety.European Medicines Agency Issued a safety warning For research.
This new study was started before the publication of the meta-analysis. The results are similar in that they suggest an increased risk of breast cancer with the use of HRT, but the results of a new study show that the risk is lower than that estimated by a meta-analysis and the risk after stopping HRT. By meta-analysis suggests that is decreasing more rapidly than suggested.
“The publicity surrounding the publication of the meta-analysis has highlighted unexpectedly high risks and raised the level of concern in some areas,” commented Vinogradova. “Our study, based on general population data, did not confirm such findings. In general, the level of risk was low and the variability in risk magnitude was revealed.”
Vinogradova said this discrepancy could be related to the fact that the studies were designed differently. Meta-analyses were conducted around the world at different times and relied on the results of 24 studies involving women of different ages and backgrounds. She said the meta-analysis study used a variety of methods, including questionnaires that could be biased because they depended on women’s memory.
In contrast, the new study analyzed electronic medical record data prospectively collected by UK general practice. The data was taken from the QResearch and Clinical Practice Research Datalink (CPRD) databases. It was the UK’s two largest primary care databases, linked to hospitals, mortality, and cancer registry.
Because the study used “consistent design” and “consistent data sources,” these new results “are likely to be more accurate and reliable for assessing risk among HRT users,” Vinogradova said. Commented.
Since this study used an observational design, it cannot be proven that HRT causes breast cancer. She added that these results could better represent women in the general UK population compared to previous meta-analyses.
Comments on new researchDr. Michael Jones, a senior staff scientist in genetics and epidemiology at the Cancer Institute in London, also emphasized that the study was extensive and the data came from medical records of general practitioners. It’s a coincidence.
“The results of this study generally confirm that they have been seen before and are well established. estrogen Plus progestogen HRT is associated with an increased risk of breast cancer, and this risk increases over time of use. But rest assured, after stopping HRT, the increased risk of breast cancer almost returns to the risk seen in non-users of HRT, “he said.
“It’s important to note that one study should not be considered alone,” he added. “Even if some risks are found that are slightly less than those reported in another meta-analysis of global epidemiological evidence recently published in 2019, women considering the use of HRT are GPs. You need to follow the advice from. “
Details of the study
In this study, researchers evaluated all types of HRT commonly prescribed in the UK over the last two decades, including topical estrogens, vaginal pessaries, and creams. They grouped HRT use recently (within the last 5 years) and past (more than 5 years ago), and HRT periods as short-term (less than 5 years) and long-term (more than 5 years). The results were adjusted for a variety of factors that could affect the risk of breast cancer, including lifestyle, smoking, drinking, other medical conditions, family history, and other prescription drug use.
The analysis included 98,611 women aged 50-79 years who were first diagnosed with breast cancer between 1998 and 2019. These women were consistent with 457,498 women who were not diagnosed with breast cancer in these years due to age and common practices. HRT use was reported in 34% (33,703) of women with breast cancer and 31% (134,391) of women without breast cancer.
Overall, the risk of breast cancer was increased with the use of most HRT drugs (adjusted odds ratio). [OR], 1.21; 95% CI, 1.19 – 1.23), compared with no HRT drug. The highest risk was the combination of estrogen and progestogen HRT (adjusted OR, 1.26; 95% CI, 1.24 – 1.29). The lowest risk was associated with estrogen-only HRT (OR, 1.06; 95% CI, 1.03 – 1.10). Estrogen cream and vaginal estrogen were not associated with an increased risk of breast cancer.
In general, the risk of breast cancer was high between recent HRT users and those receiving long-term treatment. The risk of breast cancer associated with HRT increased with age and decreased with discontinuation of treatment. Treatment for less than a year was not associated with an increased risk of breast cancer.
Women who recently received long-term combined estrogen and progestogen HRT had a 79% increased risk of breast cancer compared to those who did not use it at all (adjusted OR, 1.79; 95% CI,). 1.73 – 1.85). Among the recent long-term users of combined HRT, the risk of breast cancer was highest with norethisterone (adjusted OR, 1.88; 95% CI, 1.79 – 1.99) and lowest with dydrogesterone (adjusted OR, 1.24; 95% CI). , 1.03 – 1.48).
Women who recently received long-term estrogen-only HRT had a 15% increased risk of breast cancer compared to those who had never used it (adjusted OR, 1.15; 95% CI, 1.09 – 1.21).
Women who discontinued HRT more than 5 years ago no longer had an increased risk of breast cancer with long-term estrogen-only treatment and short-term estrogen-progestogen treatment. However, the risk of breast cancer remained elevated five years after discontinuing long-term estrogen-progestogen (adjusted HR, 1.16; 95% CI, 1.11 – 1.21).
The HRT-related risk of breast cancer increased with age over the entire duration of treatment.
Recent long-term estrogen-only treatments include 0 additional breast cancer cases per 10,000 female years in women aged 50-59 years and 8 additional cases per 10,000 female years in women aged 70-79 years, compared to when not used. It was related.
Recent long-term use of estrogen-progestogen has been associated with 15 additional breast cancer cases in women aged 50-59 years and 36 additional breast cancer cases per 10,000 women a year in women aged 70-79 years.
Past long-term use of estrogen-progestogen was associated with 0 additional breast cancer cases in women aged 50-59 years and 8 additional cases per 10,000 female years in women aged 70-79 years.
In summary, Vinogradova said the increased risk of breast cancer from HRT is “relatively small, especially for young women and women who use HRT for a limited period of time.”
She commented that the decision on whether to use HRT and which type to use should depend on the severity of the symptoms, patient factors, and the suitability of other treatment options.
“These decisions should be made through discussions between the patient and her doctor, especially for women whose studies have shown to be at greatest risk,” she concludes. “We hope that the new and more detailed information provided by our study will facilitate such prescribing decisions.”
This study was partially funded by the National Institutes of Health’s Primary Care Research School, Cancer Research UIK, and Cancer Research UK Oxford Center. Vinogradova does not disclose any relevant financial relationships. Senior author Julia Hippisley Cox was an unpaid director of Q Research and a paid director of Clin Risk until 2019. Other authors do not disclose the relevant financial relationships.
BMJ. Published online on October 28, 2020. Full text
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