Breast screening guidelines should be adapted in Down's syndrome

EDITOR—Piachaud and Rohde underlined the importance of including women with learning disabilities in screening programmes because of their reported increase in mortality from cancer, although no case of breast cancer was detected in patients with Down's syndrome.1 Patja et al observed that in Finland breast cancer was nearly as frequent in people with intellectual disabilities as in the general population.2 In the subgroup of 1012 women with Down's syndrome no breast cancer was observed, although 3.9 cases were expected.2

We conducted a national epidemiological study on mortality in France over 24 years, which showed only five deaths from breast cancer in women with Down's syndrome (68.98 expected (Fisher test; P<0.00005)).3 A study conducted in the United States found only one death when 11.65 were expected.4 In Denmark no breast cancer was found in women with Down's syndrome compared with the 7.32 expected.5

A review of the literature including our own study yields only nine cases of breast cancer in patients with Down's syndrome. This is amazingly few if we keep in mind that breast cancer is the most frequent malignant neoplasm in women and if we compare it with the hundreds of cases of leukaemia reported and treated in patients with Down's syndrome.

People with learning disabilities should benefit from screening for breast cancer just like the general population. The study of Patja et al shows its necessity.2 For women with Down's syndrome the reported studies show that breast cancer is nearly 10-fold less frequent than in the general population. Tissues from people with Down's syndrome are more vulnerable to ionising radiations and particularly x rays.

As repeated mammography may have deleterious effects, the relevance of breast cancer screening in women with Down's syndrome as it is usually done in the general population every two years is called into question. If these women are not included in such programmes we as doctors will have to determine how to manage the medical surveillance of their breasts. Possible options include repeated clinical examinations by trained professionals, ultrasonography, and magnetic resonance imaging. No experimental data currently support these recommendations, which cannot yet be viewed as guidelines but should be seriously considered in view of the likely unfavourable ratio of risk to benefit in women with Down's syndrome. As other genetic conditions are likely to be associated with a risk of breast cancer that is different (increased or decreased) from that in the general population, we recommend that specific attention should be paid to women with particular genetic conditions.