Is mammography of value in women with disseminated cancer of unknown origin?

Mammography is often requested to try to identify occult primary breast carcinoma in women with metastatic cancer of unknown primary site. This study aimed to investigate whether mammography is of use in these patients in identifying the breast as the origin of the metastatic disease. Thirty-one women with a working diagnosis of metastatic cancer underwent mammography in an attempt to determine the primary site. None of these women had a palpable breast mass. The site of presentation, pathological type of tumour, site of origin, and benefit of mammography and mammography-provoked biopsy were clarified for each patient. The patients were also followed up to determine survival. The commonest sites of presentation were lung (45%), lymph nodes (19%) and abdomen (16%). The primary sites of these cancers were identified with confidence in 27 patients (87%). The commonest known primary tumour sites were lung (45%), breast (16%) and ovary (16%). Abnormal mammograms were detected in four patients (13%), but three of these did not have breast cancer. In one, the site of origin remained indeterminate, as either breast or lung. Five (16%) had a confident diagnosis of breast carcinoma; all of these women had normal mammograms. We conclude that mammography in women presenting with metastatic disease from an unknown primary site is unhelpful and is not recommended. Furthermore, we could not demonstrate its value in women presenting with axillary lymphadenopathy.