Taiwanese and U.S. radiation oncologists have developed what they call a "more sophisticated prediction model" for local regional recurrence (LRR) after mastectomy. The goal of this new system is to offer a better definition of high risk for LRR, and help determine if certain breast cancer patients would benefit more from postmastectomy radiotherapy (PMRT).
"The role of PMRT in the management of breast carcinoma has been and is controversial since its introduction more than five decades ago," wrote Dr. Skye Hongiun Cheng and colleagues. "PMRT is generally recommended for those (patients) with four or more involved axillary lymph nodes and/or those with larger primary tumors (T3 or greater)" (International Journal of Radiation Oncology, Biology, Physics, April 2006, Vol. 64:5, pp. 1401-1409).
Cheng's group, who is from the Koo Foundation Sun Yat-Sen Cancer Center in Taipei and Duke University in Durham, NC, pointed out that there is still uncertainty as to how the criteria above interacts with other possible prognostic factors.
This study included 1,110 patients with data on six clinical risk factors: age at diagnosis, primary tumor size, axillary lymph node status, nuclear grade, lymphovascular invasion (LVI), and estrogen receptor (ER) status.
Overall, the patients in this population were young, age 40 or less (23%), at the time of diagnosis. Seventy-one percent were ER-positive, 49% were node-negative, and 45% had tumors 2 cm in diameter or smaller.
If the patients were treated before 1997, only those with four or more axillary lymph nodes or a primary tumor greater than or equal to 5 cm received PMRT. After 1997, patients with fewer than four axillary lymph nodes involved, in addition to other risk factors, were candidates for PMRT.
Before 2000, node-positive patients were treated with one of four chemotherapy regimens including AC (doxorubicin, cyclophosphamide); after 2000, node-positive ER-negative patients were treated with AC and paclitaxel.
Seventy-two percent of the patients received adjuvant chemotherapy, 72% underwent hormonal therapy, and 26% had adjuvant radiotherapy.
Based on a median follow-up time of 48 months, 86% of the women were without evident disease while 14% experience a relapse. The initial sites of relapse were local regional in 1.6% of patients. The five-year probability of any LRR was 7.2%, the authors stated in their results.
A prognostic index score was developed for LRR risk in which patients received a score from 0-6 and were then grouped into low-, intermediate-, and high-risk categories. The low-risk group was made up of 547 patients, the majority of whom (522) did not receive PMRT. In the intermediate group, there were 328 patients, 202 of whom did not undergo PMRT.
For the high-risk group of 135 women, 109 had PMRT. In this segment, the authors found that PMRT significantly improved local regional control (p = 0.0001), metastasis-free survival (p = 0.001), and overall survival (p = 0.0002). Also, LR control was significantly improved by adjuvant chemotherapy and hormonal therapy.
Patients with a prior lymph node negative status and who were less than 35 years in age were estimated to have a five-year local regional control probability of 79%. Patients with at least one positive lymph node, age greater than 38 years, and ER-positive status had a much better five-year estimated local regional control rate of 95%.
"We identified patient age, ER status, and LVI, in addition to nodal status, as important prognostic variables.... Although PMRT increased local regional control in all groups, statistically significant survival benefits were only seen in the high-risk group," the authors wrote.
This probability model should lead to more improved guidelines for selecting patients for PMRT, similar to the international prognostic index currently in use for non-Hodgkin's lymphoma. However, the authors cautioned that, ultimately, it will be up to the patient, regardless of her risk score, to decide whether the survival benefit of PMRT outweighs the burden of treatment.
By Shalmali Pal
AuntMinnie.com staff writer
April 26, 2006
Related Reading
Most women don't regret preventive mastectomy, April 10, 2006
Optimal postmastectomy radiation therapy improves survival, January 6, 2006
Prevention of local breast cancer recurrence reduces mortality 15 years later, December 16, 2005
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