Presented by Karen Long, CMD, MRT(T)
Senior Medical Dosimetrist
Tom Baker Cancer Centre in Calgary, Alberta Canada

From the AAMD 43rd Annual Meeting

Recorded 8-29-18

Introduction:  Treatment strategies for patients with synchronous bilateral breast cancers who also have indications for bilateral regional nodal irradiation (RNI) are not widely documented.  This is particularly challenging if one or both internal mammary chains (IMCs) are part of the target volume.  Some centers use 3D conformal radiation therapy (3DCRT), while others employ a dose dynamic technique, such as volumetric arc therapy (VMAT) or intensity modulated radiation therapy (IMRT).  Controversy exists as to which method is optimal.

Purpose:  To use ProKnow’s international user-base to document the current international practice of treatment for patients receiving bilateral chest wall/breast plus RNI.  A case study will be presented to describe this planning challenge.

Methods and Materials:  A survey was distributed to ProKnow’s user-base which extends to a worldwide radiation therapy community of over 3500 people.  

Results:  Survey responses were analyzed and trends are reported on numbers of patients per year, choice of treatment modality, patient specific quality control, use of deep inspiration breath hold, dosimetric planning goals and achieved dosimetry. 

Conclusions:  Dose dynamic planning such as VMAT or IMRT may improve target coverage compared to 3DCRT, but doses to the heart, left anterior descending artery (LAD) and lungs can be greater in dose dynamic plans, and this may increase the risk of long term cardiopulmonary toxicity and the rate of secondary malignancy given the long term survival of these patients.  There are no guidelines on current best practice, and this survey is intended to inform the radiation therapy (RT) community about the landscape of current practice internationally and the challenges of treating patients who have bilateral breast cancers with RT.

Learner Outcomes:

1. Be aware of the controversy in planning and treating patients with synchronous bilateral breast cancers and RNI when one or both IMCs are included in the target volume.
2. Review current international practices of treatment for patients receiving bilateral chest wall/breast plus RNI.
3. Be familiar with a 3DCRT planning technique used to treat synchronous bilateral chest wall plus RNI including bilateral IMC nodes.

Presenter:
Karen Long is a senior medical dosimetrist at the Tom Baker Cancer Centre in Calgary, Alberta Canada. She obtained her medical radiation therapy designation in 1985 after her training in Winnipeg, Manitoba and by 1992 was successful in obtaining her certified medical dosimetrist classification. Her work life has taken her to many cities including: Saskatoon, Saskatchewan, Olympia, Washington, Riyadh, Saudi Arabia and Calgary, Alberta in her more than 30 years in the field of radiation therapy. In the last 8 years she has dedicated most of her clinical efforts in the breast tumor group, being very involved in the implementation of low dose rate breast brachytherapy, deep inspiration breath hold and bilateral breast techniques at her centre in Calgary.