Radiation exposure in patients (pts) with newly diagnosed breast cancer (BC) within first year (yr) from diagnostic procedures (DP).

Abstract

123 Background: Radiation exposure is associated with an increased risk of secondary cancers. Few studies have examined radiation exposure from DP in BC. Methods: We retrospectively analyzed the cumulative radiation doses (millisievert [mSv]) of routine DP done in 305 pts during the 1st yr following BC diagnosis between Jan 2008-Oct 2010. Data regarding the frequency of DP including mammograms, sentinel lymph node biopsies, X-rays, computed tomographic (CT) and/or positron emission tomographic (PET) scans, MUGA scans and bone scans were collected. Mean radiation doses of DP were obtained from Departments of Nuclear Medicine and Radiation at our institution. Kruskal-Wallis test and post-hoc pairwise comparisons were used to assess the influence of various factors including age, histology, ER/PR (Estrogen/Progesterone) status and stage on the amount of radiation exposure. Results: Mean radiation exposure relative to various factors is shown in the Table. Pts < 40yrs had a significantly higher radiation dose as compared to pts > 60yrs (35.9mSv vs. 19.2mSv; p = 0.009). Pts with DCIS (ductal carcinoma in situ) had a significantly less radiation exposure as compared to IDC (infiltrating ductal carcinoma) and ILC (invasive lobular carcinoma) (8.5mSv vs. 26.7mSv and 22.4mSv respectively; p< 0.0001). Stage ≥ IIB disease was associated with a significantly higher radiation exposure (p< 0.0001). Stage ≥ IIIA was the only factor associated with a higher radiation dose from PET/CTs (p< 0.0001). Conclusions: Radiation exposure from DP is significant in the 1st yr of BC diagnosis, especially for younger and advanced stage pts. Risk is small but relevant, especially in younger pts. [Table: see text]