HER-2 positive breast cancer represents 20% of breast cancers. If untreated, they have a worse prognosis than HER-2-negative tumors, but adjuvant therapy with trastuzumab (TSZ) improves survival. This treatment is usually well tolerated. The more frequent adverse event (30%) is asymptomatic decrease in left ventricular ejection fraction (LVEF), evaluated in our experience by echocardiogram at the start and the end of TSZ.
We evaluated acute cardiotoxicity and skin tolerance in patients(pts) with HER2-positive disease who had undergone different adjuvant whole breast Hypofractionated Radiotherapy (HRT) schedules, after breast conservative surgery, treated with concurrent TSZ. Since TSZ gives a radio-sensitising effect to cancer and normal cells, in our analysis we also evaluated skin toxicity. All acute toxicities were assessed according to CTCAE-v3 criteria. From February 2008 to June 2017, 52 pts underwent adjuvant chemotherapy followed by TSZ and HRT. Only pts ≤pT2 and ≤pN1a were enrolled. All pts received 3-D conformal RT to whole breast in supine position with three different HRT schemes based on age: 46 Gy in 20 fractions(fx) (<40 years old) 15pts, 39 Gy in 13 fx (<46 yo) 16pts, 35 Gy in 10 fx (>46 yo) 21pts, 4 fractions at week. A concomitant boost on the tumor’s bed was given according to risk factors.
At a median follow-up of 5 years (range 6-108 months) 49pts (94%) were alive; 1 (2%) developed locoregional relapse and 2 (4%) distant metastases. 21 pts (40%) had basal cardiac risk factors. Our results about cardiotoxicity are summarized in the 46 Gy/20 fx 39 Gy/13 fx 35 Gy/10 fx Pts % Pts % Pts % 2/15 13 0/16 0 1/21 5 3/15 20 5/16 31 5/21 24 10/15 67 11/16 69 15/21 71
Differences in LVEF do not seem to be important despite HRT schemes. G1-G2 toxicities were similar to those reported in the literature, G3 toxicities did not occur. Heart and left coronary artery’s contouring has been a focus recently; this reduces the cases of cardiac strokes but does not affect LVEF. As regard skin tolerance, in our experience, HRT with TSZ seems to be well tolerated, regardless of the scheme used.
Department of Radiation Oncology
All authors have declared no conflicts of interest.