Study identifies factors that help determine risk of bone metastases in breast cancer patients

A study published in the July 2010 issue of BMC Cancer found that tumor grade (T), nodal grade (pN), and histopathology were useful factors in classifying breast cancer patients who underwent surgery as having high, medium, or low risk of developing bone metastases. The assessment was conducted to help investigators determine which patients may benefit from use of an adjuvant bisphosphonate in a clinical trial setting.

The study included 5459 consecutive breast cancer patients who underwent surgery between 1988 and 1998 and were followed up regarding bone metastasis until December 2006. At the time of surgery, patient characteristics were analyzed using Cox's method, with bone metastasis as events. Based on this analysis, patients were judged either to require the adjuvant bisphosphonate or not, and classified as high-risk (>3% person-year), medium-risk (1-3%), and low-risk (<1%).

The investigators found that the incidence of bone metastasis was constant at between 1.0% and 2.8% per person-year for more than 10 years. Non-invasive cancer had a very low incidence of bone metastasis, occurring in 1 of every 436 patients. Because T and pN were found to be important factors for bone metastasis prediction, patients were placed in subgroups based on their pTNM stage. Patients with stage IIIA, IIIB, and IV disease had a bone metastases incidence of >3% per person-year. The incidence was <1% per person-year in those with stage I disease and between 1% and 3% in those with stage II disease. When histopathology data were included in the analysis, patients with stage IIB disease and high-risk histology also had a high incidence of bone metastases at 3% per person-year, whereas those with stage IIA disease and medium-risk histology had a low incidence at <1% per person-year.

The authors concluded that bone metastasis incidence remained constant for many years in the patients they observed and note that the use of pN, T, and histopathology findings can be used to classify breast cancer patients as having high, medium, or low risk for bone metastases following surgery.

Full article available here.