Breast cancer screening
Women of 50-69 years of age are invited by personal letter take part in breast cancer screening, or mammography, every two years.
More than 80% of the women invited to attend are screened. Fewer than 3% of participants are invited for further testing, i.e. ultrasound examination and biopsy, and of them about 20% have breast cancer (link to statistics).
Altogether about 5 000 women in Finland each year are diagnosed with breast cancer. Of those, over half of them are of the screening age group of 50-69. Some two-thirds of female breast cancers are detected by screening. The remaining breast cancers are found in non-screened individuals or among participants in screening whose cancer did not appear in screening or only appeared after mammography (1. Sarkeala et al., 2014).
The impact of screening on breast cancer mortality has been studied in Finland since the 1990s. Between 1992 and 2003, mortality among women who had been invited to take part in screening was 22% lower compared to the situation when screening had not been arranged (2. Sarkeala et al. 2008). The mortality of screening participants was 28% lower. The impact of screening on breast cancer mortality was also investigated in the late 2000s and the result has remained unchanged (3rd Heinävaara et al., 2016).
In international studies, screening has been shown to reduce breast cancer mortality even at the age of 70-74 (4. Lauby-Secretan et al. 2016). Extending screening to this age group should be considered.
DOWNSIDES OF SCREENING
In addition to benefits, screening of breast cancer also entails drawbacks. One in five women regularly participating in screening is sent unnecessarily for further tests on at least one occasion (5. Hofvind et al. 2012).
Screenings also indicate small early stage tumours, some of which would not cause symptoms during a woman’s lifetime. Studies show, however, that these constitute at most a tenth of the breast cancer tumours among women who have participated in screening (6. Puliti et al. 2012, 7. Heinävaara et al. 2014).
Rintasyövän seulontaohjelman tärkeimmät tunnusluvut vuodelta 2015 löytyvät oheisesta raportista (Ahti, Maiju ja Milla tekevät, valmistuu graafikolta elo-syyskuussa).
Sarkeala T, Luostarinen T, Dyba T, Anttila A. Breast carcinoma detection modes and death in a female population in relation to population-based mammography screening. SpringerPlus 2014; 3: 348.
Sarkeala, Heinävaara S, Anttila A. Organised mammography screening reduces breast cancer mortality: A cohort study from Finland. Int J Cancer 2008; 122: 164–9.
Heinävaara S, Sarkeala T, Anttila A. Impact of organised mammography screening on breast cancer mortality in a case-control and cohort study. Br J Cancer, doi: 10.1038/bjc.2016.68.
Lauby-Secretan B, Scoccianti C, Loomis D ym. Breast cancer screening – viewpoint of the IARC working group. NEJM 2015; 372: 2353-58.
Hofvind S, Ponti A, Patnick J ym. False-positive results in mammographic screening for breast cancer in Europe: a literature review and survey of service screening programmes. J Med Screen 2012; 19 (Suppl 1): 57–66.
Puliti D, Duffy SW, Miccinesi G ym. Overdiagnosis in mammographic screening for breast cancer in Europe: a literature review. J Med Screen 2012; 19 (Suppl 1): 42–56.
Heinävaara S, Sarkeala T, Anttila A. Overdiagnosis due to breast cancer screening: updated estimates of the Helsinki service study in Finland. Br J Cancer 2014; 111(7): 1463–8.