To assess influence of stage at breast cancer diagnosis, tumour biology, and therapy on survival in contemporary times of better (neo-)adjuvant systemic therapy.
Prospective nationwide population based study.
Female primary breast cancer patients diagnosed between 1999 and 2012 (173,797). Participants were subdivided into two time cohorts on the basis of breast cancer diagnosis; 1999 through 2005 (n = 80,228) and 2006 through 2012 (n = 93,569). Main outcome measures were relative survival, compared between both cohorts, and the influence of traditional prognostic factors on overall mortality, analyzed with Cox regression for both cohorts separately.
Compared to 1999-2005 patients from 2006-2012 had smaller ( ≤ T1 65 vs. 60%; p < 0.001), more often lymph node negative (N0 68 vs. 65%; p < 0.001) tumours, but they received more chemotherapy, hormonal therapy, and targeted therapy (neo-adjuvant/adjuvant systemic therapy 60 vs. 53%; p < 0.001). Median follow-up was 9.8 years for 1999-2005 and 3.9 years for 2006-2012. Relative 5-years survival rate was 96% in 2006-2012, improved in all tumour and nodal stages compared to 1999-2005, and 100% in tumours ≤ 1 cm. With multivariable analyses, adjusted for age and tumour type, overall mortality decreased by surgery (especially breast conserving), radiotherapy and systemic therapies. Mortality increased with progressing tumour size in both cohorts (2006-2012 T1c vs. T1a HR 1.54, 95% CI 1.33 to 1.78), but without significant difference in invasive breast cancers until 1 cm (2006-2012 T1b vs. T1a HR 1.04, 95% CI 0.88 to 1.22), and independently with progressing number of positive lymph nodes (2006-2012 N1 vs. N0 HR 1.25, 95% CI 1.17 to 1.32).
Tumour stage at breast cancer diagnosis influences overall survival significantly also in the current era of effective systemic therapy. Early tumour stage at breast cancer diagnosis remains vital.
Conflict of interest: none declared. Financial support: none declared. ICMJE forms provided by the authors /are available online along with the full text of this article.