Palpable breast cancer which is mammographically invisible.

We have evaluated tumour characteristics, local recurrence rates and prognostic markers in 40 women with symptomatic palpable breast cancer proven by cytology, but in whom routine two-view mammography failed to detect a radiological abnormality. False negative mammograms were identified by cross-referencing all negative mammograms performed at the Royal Victoria Infirmary during the period 1995-1999, with pathological records at the same institution. The average age was 48 years. The majority of the tumours were invasive ductal carcinomas, 35 with an average size of 24 mm. There were 16 Grade II and 15 Grade III tumours. Lymphovascular invasion was seen in 18 on histology and six patients had distant metastases. Of those patients treated by conservation therapy there has been only one local recurrence, with a median follow-up of 18 months. We conclude that mammographically invisible tumours are of common histological type, are frequently high grade and node positive and occur mainly in the younger age group. However, BCT remains a viable option in the treatment of these tumours.