The German Breast Cancer Study Group (GBSG2) dataset studies the effects of hormone treatment on recurrence-free survival time. The event of interest is the recurrence of cancer time. This data frame contains the observations of 686 women:

• horTh: hormonal therapy, a factor at two levels (yes and no).
• age: age of the patients in years.
• menostat: menopausal status, a factor at two levels pre (premenopausal) and post (postmenopausal).
• tsize: tumor size (in mm).
• tgrade: tumor grade, a ordered factor at levels I < II < III.
• pnodes: number of positive nodes.
• progrec: progesterone receptor (in fmol).

• estrec: estrogen receptor (in fmol).

• time: recurrence free survival time (in days).

• cens: censoring indicator (0- censored, 1- event).

References

• W. Sauerbrei and P. Royston (1999). Building multivariable prognostic and diagnostic models: transformation of the predictors by using fractional polynomials. Journal of the Royal Statistics Society Series A, Volume 162(1), 71–94
• M. Schumacher, G. Basert, H. Bojar, K. Huebner, M. Olschewski, W. Sauerbrei, C. Schmoor, C. Beyerle, R.L.A. Neumann and H.F. Rauschecker for the German Breast Cancer Study Group (1994), Randomized 2 × 2 trial evaluating hormonal treatment and the duration of chemotherapy in node- positive breast cancer patients. Journal of Clinical Oncology, 12, 2086–2093