Staging systems for breast cancer were developed primarily to select similar groups of patients for treatment comparisons, rather than to determine prognosis. Jimenez-Lee and colleagues believe that breast cancer outcomes in breast cancer may be predicted more accurately by tumor characteristics that are poorly represented in current staging systems. They developed a prognostic tool based on tumor biology and tested it in more than 400 patients.
The breast cancer severity scale (BCSS) is based on the sum of points allocated for tumor diameter, number of positive lymph nodes, and hormone receptor status. One point was awarded for tumor diameter up to 1 cm, two points for tumors between 1.1 and 2.0 cm, three points for those 2.1 to 5.0 cm, and four points for tumors with a diameter greater than 5.1 cm. Patients with one to three positive lymph nodes scored one point, those with four to nine positive nodes scored five points, and those with 10 or more positive nodes scored 10 points. If estrogen or progesterone receptors were absent, one point was given; if both hormone receptors were absent, two points were added to the score.
The researchers applied the scoring system to data on 417 patients with breast cancer who were treated at a university medical center between 1997 and 2002. The mean age of the patients was 57 years, and the median duration of follow-up was 20 months. Using the American Joint Commission on Cancer staging criteria, 171 patients were stage I, 190 were stage II, 28 were stage III, and 30 were stage IV. The mean BCSS was 2.4 for patients with stage I cancer, 4.7 for those with stage II cancer, 7.9 for those with stage III cancer, and 7.0 for those with stage IV cancer.
All patients with stage I cancer survived for five years. The other overall five-year survival rates were 97 percent for patients with stage II cancer, 68 percent for those with stage III cancer, and 18 percent for those with stage IV cancer. For disease-free survival, the five-year rates were 95 percent for patients with stage I cancer, 91 percent for those with stage II cancer, and 55 percent for those with stage III cancer.
The BCSS provided better prognostic information than conventional staging. A BCSS score of seven points discriminated between patients with a good prognosis and those with a poor prognosis. The five-year survival rate for patients with a BCSS score below seven points was 92 percent, compared with 44 percent for those with higher scores. This discrimination was even better when patients with stage IV were excluded: the five-year survival rate was 99 percent for patients with scores below seven points, compared with 75 percent for patients with higher scores. The comparable disease-free survival rates were 93 percent for patients with scores below seven points and 60 percent for patients with scores above seven points.
The authors conclude that the BCSS is a simple method for determining overall survival and disease-free survival using readily available data. They believe that patients and physicians could use the scoring system to guide treatment decisions.