Adjuvant Regional Irradiation after Breast-conserving Therapy for Early Stage Breast Cancer: a Survey of Canadian Radiation Oncologists

Abstract 

Aims

To document the use of adjuvant regional irradiation after breast-conserving therapy for early stage breast cancer by Canadian radiation oncologists and to identify the factors influencing their clinical decisions.

Materials and methods

We conducted a survey to assess the above aims. In April 2008, a questionnaire was sent to 167 members of the Canadian and Quebec Associations of Radiation Oncologists with interest in breast cancer management. The answers were obtained through a dedicated website, which collected the raw data collected for analysis.

Results

In total, 67 radiation oncologists completed the survey, corresponding to a 40% response rate. Most respondents were experienced and high-volume providers. We identified several areas of variation in the decision-making regarding regional lymph node irradiation after breast-conserving therapy. Regarding the decision to combine regional nodal irradiation with irradiation of the breast, the number of positive nodes after axillary dissection (1–3 vs ≥4) was a crucial determinant. For patients with between one and three positive nodes and a nodal ratio of 50%, most respondents added regional irradiation. Similarly, the same nodal ratio of 50% was the main factor for inclusion of the axillary nodal region in the radiation field. However, few radiation oncologists have chosen to include the internal mammary chain in their treatment plan. The number of positive lymph nodes, the nodal ratio, the number of lymph nodes removed and the presence of extracapsular extension were the primary self-reported factors that directed the decision to offer regional radiotherapy.

Conclusions

This survey showed that there is a wide variation of practices among radiation oncologists in Canada. These results support the need for treatment guidelines and provide guidance on which factors should be included in a decision-making algorithm.

Key words: Adjuvant irradiation, breast cancer, Canadian radiation oncologists, survey