The prognosis of small primary breast cancers.

The Nottingham Prognostic Index (NPI) is an integrated prognostic index used to predict patient survival for women with invasive breast cancer. The index is based on invasive tumour size, histological lymph node stage and tumour grade. The value of such an index has been questioned in small invasive breast cancers and it has been suggested that size is the only necessary prognostic determinant. The aims of this study were to determine the extent of regional lymph node involvement and survival in women with small invasive breast cancers and to assess the value of the NPI. Between 1976 and 1994, 2684 women aged < or = 70 years were treated for primary operable invasive breast cancers of < or = 5 cm in maximum diameter, of which 318 measured < or = 1 cm. Follow-up data were evaluated to determine histological factors important in predicting survival outcomes in women with cancers < or = 1 cm in diameter and comparing their survival according to the NPI with all women treated for primary operable breast cancers < or = 5 cm in maximum diameter. Histological lymph node involvement was demonstrated in 56/318 (18%) of cancers of < or = 1 cm in diameter. Significant survival differences were demonstrated for small breast cancers according to lymph node stage, vascular invasion and histological tumour grade. Only lymph node stage and histological tumour grade were independent prognostic indicators using a multivariate Cox model. The survival curves for small tumours stratified by the NPI were similar to those of cancers up to 5 cm in diameter. The results indicate that lymph node staging and histological grading are still important prognostic determinants for breast cancers < or = 1 cm in diameter. An axillary node staging procedure should be performed for all invasive breast cancers < or = 1 cm in diameter. The NPI remains relevant for small breast cancers.