Prognostic importance of palpability as a feature of screen-detected breast cancers

Abstract

Objectives: To determine epidemiological characteristics of palpability as a feature of asymptomatic invasive breast cancers detected through screening mammography, and to determine whether palpability is predictive of case survival after adjusting for conventional prognostic indicators such as diameter, grade and nodal status. Setting: The University of Adelaide, South Australian Department of Health, and The Cancer Council South Australia, Adelaide, South Australia. Methods: Sociodemographic and clinical characteristics of 2108 screen-detected invasive breast cancers were compared by tumour palpability using univariate and multiple logistic regression analysis. Survival outcomes from breast cancer were compared using Kaplan-Meier product-limit estimates. Multivariable proportional hazard regression was employed to assess the association of palpability with survival after adjusting for conventional prognostic indicators. Results: Palpability was associated with year of diagnosis, ductal histology type, and unfavourable prognostic indicators such as larger tumour diameter, higher grade and nodal involvement. After adjusting for these variables, no associations were found with age at diagnosis, place of residence or socioeconomic status, or with presence of multifocal disease or presence of an extensive in situ component. Palpability was predictive of death from breast cancer in an unadjusted analysis, the relative risk (95% confidence limits) being 1.75 (1.12, 2.74). After adjusting for nodal involvement and larger tumour size, the relative risk no longer was elevated, reducing to 0.99 (0.60, 1.64). Discussion: Palpability is associated with unfavourable prognostic indicators, such as larger diameter, higher grade and nodal involvement, and is not an independent indicator of survival outcome for screen-detected female-breast cancers after accounting for nodal involvement and diameter.