The goal of this prospective study is to investigate the role of axillary reverse mapping (ARM) in radiation therapy planning of patients with breast cancer. Lymphedema is a common side effect after surgery and radiation therapy for breast cancer. The use of ARM is becoming more routine in surgery to differentiate the upper extremity lymphatics (UELs) from the breast axillary drainage to preferentially spare the UELs and reduce the rates of lymphedema.
Study Type
OBSERVATIONAL
Delineation of the upper extremity lymphatics (UEL) during the radiation treatment planning process using axillary reverse mapping (ARM)
ARM uses dye to track lymphatic flow of the upper extremities.We hypothesize that iodinated contrast injected into the upper inner arm (same site that surgeons inject during ARM) 15 minutes before the time of CT simulation will similarly be able to track the UELs. We will contour the visible iodinated dye and will measure if that anatomically correlates with the general known location of the UELs. Two radiation oncologists will independently determine if they can delineate the UELs. If both radiation oncologists can identify and contour the UELs in a reproducible fashion, we will code the patient as "UEL identified." If one or both physicians are either not able to identify the UEL on CT images or the contoured UEL structures are significantly different from each other, we will code the patient as "UEL not identified."
Time frame: Baseline to 1 year
Dosimetric endpoint
We will measure the Dmax, Dmin, Dmean, D25%, and D75%. Dmax is the maximum dose (in units of Gray) delivered to the UEL, while Dmin is the minimum dose and Dmean is the mean dose. D25% and D75% are the minimum dose delivered to 25% and 75% of the UEL, respectively. We will also look at the percent of theoretical radiation plans that could be safely modified. This will be a binary outcome: either the plan can be modified safely, or it cannot.
Time frame: Baseline to 1 year
Lymphedema rate
We will measure the lymphedema rates before the start of radiation and at 6 months, 12 months, 24 months, 36 months, and 60 months after the end of radiation therapy. Arm circumference will be measured 15 cm above the medial epicondyle (upper arms) and 15 cm below the medial epicondyle (lower arms. An increase in arm circumference of at least 10% in the lower arm or the upper arm, or both, compared with the contralateral arm at the same time-point will be considered clinically significant lymphedema.
Time frame: Baseline to 5 years post-treatment
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