Reduction in hormone replacement therapy use and declining breast cancer incidence in the Belgian province of Limburg

Abstract

Breast cancer is the most common female cancer in Europe, but its incidence and mortality are rapidly changing across Europe. The early termination of the women's health initiative (WHI) trial, after the detection of an increased breast cancer risk in hormone replacement therapy (HRT) users, was followed by strong declines of HRT use worldwide. We investigated whether the reduction of HRT sales affected breast cancer incidence in the Belgian province Limburg. All women registered in the Limburg Cancer Registry with a diagnosis of invasive breast cancer diagnosed between 1/1/1996 and 31/12/2005 were included in the study. Data on the use of HRT in the population were obtained from the vendors and the social security system. For age-standardization using the direct method, the European standard population was taken. In 2003 and 2004, the breast cancer incidence rate decreased significantly as compared to 2002 for women aged between 50 and 69 years. This sudden drop in the incidence intercepted a markedly increasing trend until 2002, but was followed again by an increase in 2005. Between 2002 and 2006, the sales of HRT (about 75% to women aged 50-69 years) were reduced by 41%. Breast cancer incidence was maximally related to HRT use in the previous year (R 2 = 77%). The decrease of breast cancer incidence in the Belgian province of Limburg may largely be related to the fall of HRT use following the early termination of the WHI trial. This suggests that HRT stimulates the growth of preexisting, clinically latent tumours that may not otherwise become clinically apparent.

Reductions in use of hormone replacement therapy: effects on Swedish breast cancer incidence trends only seen after several years

“…Lobular cancers have also been postulated to be particularly sensitive to hormonal stimulation. While a few investigators have reported larger recent decreases in incidence for lobular cancers than for ductal cancers [14,20], we found no evidence of a different incidence pattern for the small subgroup of lobular carcinomas available for analyses in the present study.…”

“…In an analysis based on data from nine US cancer registries, Ravdin et al reported a 7% overall decrease in incidence between 2002 and 2003 in women older than 50 years of age and particularly for estrogen receptor positive tumors [1]. Subsequent studies from the US, Canada, Australia, France, Switzerland, Germany, Great Britain, Belgium, and the Nordic countries have also reported reductions in breast cancer incidence [2][3][4][5][6][7][8][9][10][11][12][13][14]. These changes have been hypothesized to be a result of a dramatic decline in the use of hormone replacement therapy (HRT) following the 2002 release of the report from the Women's Health Initiative (WHI) hormone trial [15].…”

Changing pattern of age-specific breast cancer incidence in the Swiss canton of Geneva

“…The association with HRT use is stronger for lobular carcinoma than for ductal carcinoma [17,18]. In Belgium, Vankrunkelsven et al [7] found a larger decline in invasive lobular than in ductal carcinomas, while inverse results were found in the USA [19]. For Geneva, we previously reported a disproportionate increase in lobular cancer incidence during the period 1976-1999.…”

“…After that the Women's Health Initiative (WHI) randomized controlled trial in 2002 reported an increased breast cancer risk among women using hormone replacement therapy (HRT) [1,2], HRT use and breast cancer incidence among post-menopausal women showed an important decline in several countries, including USA, Belgium, France, Australia, United Kingdom, and Germany [3][4][5][6][7].…”

Hormonersatztherapie nach Mamma- und Ovarialkarzinom

“…Sie führen diese Reduktion auf den Rückgang der HRT zurück [26]. Dieser Kausalzusammenhang kann zum einen durch Daten aus Deutschland [20,21], zum anderen aber auch mit Daten aus Frankreich [1], Belgien [30] und Australien [6] postuliert werden. Daher ist von einer zunehmenden Zahl langfristig überleben-der Mammakarzinompatientinnen auszugehen.…”