The .dat file gives the data for a part of a large clinical trial
carried out by the Radiation Therapy Oncology Group in the United States.
The full study included patients with squamous carcinoma of 15 sites in
the mouth and throat, with 16 participating institutions, though only data
on three sites in the oropharynx reported by the six largest institutions
are considered here. Patients entering the study were randomly assigned to
one of two treatment groups, radiation therapy alone or radiation therapy
together with a chemotherapeutic agent. One objective of the study was to
compare the two treatment policies with respect to patient survival.