Dose to LAD Might Be Critical in Prone Whole Breast Irradiation -- A Dosimetric Comparison of Coronary Arteries and Heart in Prone Versus Supine Whole-breast Irradiation

Volume 84  Number 3S  Supplement 2012

Oral Scientific Sessions

In Arm 1, 65% had stage I-II invasive breast cancer (9% with N1 disease) and 35% DCIS. In Arm 2, 77% had stage I-II invasive breast cancer (12% with N1 disease) and 23% DCIS. Baseline self-evaluation of cosmesis was the same in the 2 arms: 94% of patients report a good-excellent result, 6% report a fair result. Acute radiation toxicity is detailed in the Table. The percentage of patients with grade 2 or 3 wet desquamation was not significantly different in the daily arm compared to the weekly arm (6.5% vs. 3.5%, Fisher’s exact test, p Z 0.25, 2-sided). Conclusions: A tumor bed boost delivered either daily or weekly during prone A-IMRT to the breast results in comparable acute toxicity. Longer follow-up is needed to establish efficacy, late toxicity, and cosmetic results of each boost approach. Author Disclosure: E.O. Osa: None. N. Huppert: None. M. Fenton-Kerimian: None. J.D. Goldberg: None. G. Jozsef: None. K. DeWyngaert: None. S.C. Formenti: None.

209 Intensity Modulated Radiation Therapy With Integrated Boost After Breast Conservative Surgery in Breast Cancer Patients: A Prospective Study R. Peng, S. Wang, Y. Li, Y. Song, W. Wang, J. Jin, Y. Liu, X. Liu, Z. Yu, and H. Ren; Cancer Institute and Hospital, Chinese Academy of Medical Sciences, Beijing, China Purpose/Objective(s): To prospectively evaluate the feasibility of intensity modulated radiation therapy (IMRT) with integrated boost after conservative surgery in breast cancer patients. Materials/Methods: From January 2006 to June 2010, a total of 128 breast cancer patients with stages I-III diseases were recruited. All received whole breast IMRT with integrated tumor bed boost after breast conservative surgery with negative margins. Clips were routinely placed around the surgical cavities. A total dose of 50 Gy in 25 fractions with 2 Gy per fraction was delivered to the whole breast, while 60 Gy with 2.4 Gy per fraction was delivered to the tumor bed concomitantly. Supraclavicular fossa was irradiated to 50 Gy in 9 patients (7.1%) who had more than 3 involved axillary lymph nodes. 104 patients (81.3%) received chemotherapy. Ninety-three (94.9%) of the 98 patients who had positive receptor received endocrine therapy. Breast photographs were taken for every patient before and after radiation therapy. Cosmetic evaluation is based on the Harvard system. Results: With a median follow-up of 26 months (range; 10-72 months), 100 patients (77.3%) had “excellent or good” cosmetic outcome after radiation therapy, compared to 110 patients (85.9%) before radiation therapy. However, 28 patients (21.9) had “fair” cosmetic outcome and 1 patient had “poor” appearance after radiation therapy. Regarding the influence of radiation therapy, 18 patients (14.1%) experienced improved cosmetic outcome after radiation therapy while 34 patients (26.6%) had an inferior appearance. The acute skin toxicity was grade1 in 65.6%, grade 2 in 15.6%, and grade 3 in 2.3% of all patients. Grade 2 radiation pneumonitis (RP) developed in 3.8% of this cohort, grade 1 in 22.5%. No patient had grade 3 or higher RP. Five patients had recurrent diseases, 1 in the ipsilateral breast and 4 in the distant areas. The locoregional recurrence rate at 2 years was 0.8%, the 2-year overall survival rate was 99.2%, and 2year disease-free survival rate was 96.8%, respectively. Conclusions: IMRT with integrated boost after breast-conserving surgery for breast cancer patients is well tolerated, with relatively good cosmetic

Oral Scientific Abstract 209; Table VARIABLE Age (years) 45 <45 Menopausal status Postmenopausal Premenopausal Estrogen receptor Positive Negative

36 (28.2) 92 (71.9) 97 (75.8) 31 (24.2)

outcome and moderate toxicity. Meanwhile, short-term local control and survival are excellent. Author Disclosure: R. Peng: None. S. Wang: None. Y. Li: None. Y. Song: None. W. Wang: None. J. Jin: None. Y. Liu: None. X. Liu: None. Z. Yu: None. H. Ren: None.

210 Dose to LAD Might Be Critical in Prone Whole Breast Irradiation – A Dosimetric Comparison of Coronary Arteries and Heart in Prone Versus Supine Whole-breast Irradiation F. Wuerschmidt,1 S. Stoltenberg,1 M. Kretschmer,1 S. Heyden,1 and C. Petersen2; 1Radiologische Allianz Hamburg, Hamburg, Germany, 2 Clinic for Radiation Therapy and Radiooncology, UKE, Hamburg, Germany Purpose/Objective(s): Sparing of normal lung is best achieved in prone whole breast irradiation (WBI). However, exposure of heart and coronary arteries might increase due to anterior movement of the heart in prone WBI. Materials/Methods: Treatment plans of 46 patients with large breasts irradiated for breast cancer after breast conserving surgery were analyzed. The average treated breast volume of right-sided breasts (n Z 33) was 1,804 ccm (range 553 e 3,735 ccm) and 1,500 ccm (553 e 2,904 ccm) for left-sided (n Z 13), resp. The majority had invasive cancer (96%) of which 61% were pT1 and 39% pT2 tumors. All pts received radiation therapy to the breast only. The boost dose was not considered for plan evaluation. For 3D treatment planning, all pts underwent a non-contrast enhanced CT in supine position with wingboard and a second CT in prone position using a prone breastboard (Orfit). Written informed consent was obtained from all pts. Non-target volumes of heart and coronary arteries (RCA -right coronary artery; LAD - left descending artery; CX - left circumflex artery) were contoured. The data were prospectively collected. For each position, we used a field-in-field technique to avoid wedges. The PTV was encompassed by the 95%-isodose. Dose-distributions were reviewed in 3D and using dose-volume-histogram (DVH) data. A total of 50.4 Gy in 28 fractions over 5 weeks was prescribed. Differences were calculated for each patient and compared using the Wilcoxon signed-rank test. Results: Treatment of left-sided breasts resulted in similar maximum and mean heart doses in prone versus supine WBI (46.5 Gy/4.2 Gy vs. 47.4 Gy/4 Gy; p Z 0.70). The RCA and LAD generally had higher dose exposure in left versus right WBI independent of position. Prone WBI always resulted in significantly higher exposures of RCA, CX, and LAD as compared to supine WBI except for maximum LAD dose in left WBI. In left WBI mean LADprone was 33.5 Gy (range 6.3 to 49.6 Gy) versus LADsupine 25.6 Gy (4.1 to 48.2 Gy; p Z 0.005). V20prone was 73.6% versus V20supine 50.4% (p Z 0.001); V40prone 46.4% versus V40supine 33.2% (p Z 0.023). Doses to RCA and CX were much lower with maximum and mean of 3.5/2.6 Gy in prone WBI versus 3.3/2.3 Gy in supine WBI of right breasts (n.s.). Scatter dose to RCA was significantly higher in left prone WBI (mean 2 Gy; max. 2.5 Gy) versus left supine WBI (1.7 Gy; 1.4 Gy; p < 0.001) though the clinical relevance is doubtful. The CX received max.doses of 0.7 Gy in prone WBI versus 0.6 Gy in supine WBI. Conclusions: Heart dose is not different between supine and prone WBI. However, in left WBI unwanted exposure of the LAD with clinically relevant doses can be markedly higher in prone WBI. We recommend

Patient characteristics

No. of Patients (%) 70 (54.7) 58 (45.3)

S85

VARIABLE Progesterone receptor positive negative HER 2 1+ 2+ 3+ negative

No. of Patients (%) 91 (71.1) 37 (28.9) 35 24 19 50

(27.3) (18.8) (14.8) (39.1)

VARIABLE T stage T1 T2 T3 N stage N0 N1 N2 N3

No. of Patients (%) 93 (72.7) 34 (26.6) 1 (0.8) 97 22 8 1

(75.8) (17.2) (6.2) (0.8)

VARIABLE Stage I II III Histological grade I II III Unknown

No. of Patients (%) 76 (59.4) 43 (33.6) 9 (7.1) 7 70 37 14

(5.5) (54.7) (28.9) (10.9)

S86

International Journal of Radiation Oncology  Biology  Physics

planning CT scans in prone and supine position and contouring of the LAD for plan evaluation of WBI. Author Disclosure: F. Wuerschmidt: None. S. Stoltenberg: None. M. Kretschmer: None. S. Heyden: None. C. Petersen: None.

Purpose/Objective(s): Limited data is available comparing clinical outcomes using alternative accelerated partial breast irradiation (APBI) schedules. The purpose of this analysis was to compare efficacy between a 2-day and 5-day schedule in women with early-stage breast cancer. Materials/Methods: Patients were treated between June 2000 and January 2011 at a single institution with balloon-based brachytherapy using either a 2-day (2,800 cGy in four 700 cGy BID fractions) or a traditional five-day (3,400 cGy in ten 340 cGy BID fractions) fractionation pattern. The CTV consisted of a 1cm expansion from the balloon surface and a single-lumen device was used in all cases. To compare efficacy between the two treatment approaches, a matched-pair analysis was performed using a one to two ratio which successfully paired 38 two-day patients with 76 five-day patients. Match criteria included minimal length of follow-up 1.0 yr, clinical stage, age (+/- 3 yrs), and ER status. Clinical outcomes analyzed include local recurrence (LR), regional recurrence (RR), distant metastases (DM), disease-free survival (DFS), cause-specific survival (CSS), and overall survival (OS). Results: In comparing clinical-pathological traits of the two groups, no significant differences were noted for age (p Z 0.838), clinical stage (p Z 1.000), ER status (p Z 1.000), tumor size (p Z 0.236), margin status (p Z 0.556), nodal stage (p Z 0.381), PR (p Z 0.749), use of adjuvant chemotherapy (p Z 0.927) or endocrine therapy (p Z 0.129). Per the ASTRO Consensus Guidelines, no differences were noted in the distribution of clinical groups between the 2- and 5-day treatment cohorts with the majority of patients categorized as suitable or cautionary (2-day: 92% vs. 5-day: 87% p Z 0.436). With a mean follow-up of 4.7 yrs (4.9 yrs for 2-day vs. 4.5 yrs for 5-day, p Z 0.279), no differences were seen in the 5year actuarial rates of LR (0.0% vs. 2.6%, p Z 0.359), DFS (94.4% vs. 96.1%, p Z 0.618), CSS (100% vs. 94.9%, p Z 0.207), or OS (97.3% vs. 92.5%, p Z 0.811) between the 2-day and 5-day APBI groups, respectively. There was no RR in either group. Rate of DM was similar for both the 2 and 5-day patients (5.6% vs. 1.3%, p Z 0.456). Conclusions: With near 5-year follow-up for the 2-day schedule, APBI treated with the 2-day regimen produced clinical outcomes that were equivalent to the 5-day schema of dose delivery. Reduction in days ontreatment afforded by such hypofractionation offers more flexibility in both clinical and patient scheduling. Further follow-up and increased numbers of treated patients will be needed to substantiate equivalence of adjuvant hypofractionated APBI. An HIC-approved protocol randomizing patients between the 2 versus 5-day treatment schemes is currently open for accrual at our institution. Author Disclosure: P.Y. Chen: None. C. Shah: None. J. Wilkinson: None. M. Wallace: None. H. Ye: None. A. Fowler: None. N. Dekhne: None. P. Benitez: None. D.S. Brabbins: None. I.S. Grills: None.

211 Should Ductal Carcinoma In Situ (DCIS) be Removed From the ASTRO Cautionary Group for Off-protocol Use of Accelerated Partial Breast Irradiation (APBI)? A Pooled Analysis of Outcomes for 300 Patients With DCIS treated With APBI C.S. Shah,1 F. Vicini,2 J. Wilkinson,1 M. Keisch,3 P. Beitsch,4 and M. Lyden5; 1William Beaumont Hospital, Royal Oak, MI, 2Michigan Healthcare Professionals, Farmington Hills, MI, 3Cancer Healthcare Associates, Miami, FL, 4Dallas Surgical Group, Dallas, TX, 5Biostat Inc., Tampa, FL Purpose/Objective(s): Limited data have been published regarding the validity of the ASTRO Consensus Panel (CP) guidelines and ductal carcinoma in situ (DCIS). The purpose of this study was to analyze patients with DCIS treated with APBI within a pooled set of patients treated on the American Society of Breast Surgeons (ASBrS) MammoSite Registry Trial. Materials/Methods: A total of 300 women with DCIS underwent APBI between April 1993 to November 2010 as part of the ASBrS Registry Trial (n Z 192) or at WBH (n Z 108). Patients with pure DCIS 3 cm (n Z 125) were assigned to the cautionary risk group per ASTRO CP guidelines and analyzed compared to the pooled invasive suitable (n Z 653) group and pooled invasive suitable/cautionary (n Z 1,298) group with regards to ipsilateral breast tumor recurrence (IBTR), regional recurrence (RR), distant metastases (DM), disease-free survival (DFS), cause-specific survival (CSS), and overall survival (OS). Results: Median age was 62 years (range: 50-83 years) and median tumor size was 6.0mm (range: 0.0-28.0 mm). DCIS patients were younger, with higher grade but smaller tumors, and were more likely to have close margins compared with the pooled suitable and suitable/cautionary groups. The rate of IBTR for all DCIS patients was 1.6% at five years with no RR or DM noted while CSS was 100% and OS was 95.8%. No differences in IBTR (1.6% vs. 2.4%, p Z 0.68), RR (0% vs. 0.4%, p Z 0.47), DM (0% vs. 0.8%, p Z 0.32), DFS (100% vs. 96.3%, p Z 0.14), or CSS (100% vs. 98.6%, p Z 0.22) were noted between DCIS patients and pooled invasive suitable patients. OS, however, was improved in DCIS patients (95.8% vs. 90.9%, p Z 0.03). Similar findings were seen for DCIS versus invasive suitable/cautionary patients including no differences in IBTR (1.6% vs. 3.1%, p Z 0.46), RR (0% vs. 0.6%, p Z 0.40), DM (0% vs. 2.5%, p Z 0.11), or CSS (100% vs. 98.3%, p Z 0.16) but improved DFS (100% vs. 94.4%, p Z 0.04) and OS (95.8% vs. 90.8%, p Z 0.03) were seen in DCIS patients. Findings were similar for DCIS patients 60 years and older (n Z 74), except that OS was not significantly different. Conclusions: Excellent clinical outcomes were seen for both patients with invasive breast cancer within the suitable group as well as those with DCIS within the cautionary subgroup (98.4% local control at 5-years) despite more aggressive clinical-pathologic features in the DCIS cohort. This analysis of the largest published data of patients with DCIS treated with APBI supports consideration for removal of DCIS from the cautionary risk group as outcomes are similar (and excellent) in a large pooled analysis. Author Disclosure: C.S. Shah: None. F. Vicini: None. J. Wilkinson: None. M. Keisch: None. P. Beitsch: None. M. Lyden: None.

212 Clinical Efficacy of 2- Versus 5-day Accelerated Partial Breast Irradiation Delivered via Balloon-based Brachytherapy: Results of a Matched Pair Analysis P.Y. Chen,1 C. Shah,1 J. Wilkinson,1 M. Wallace,1 H. Ye,1 A. Fowler,1 N. Dekhne,2 P. Benitez,2 D.S. Brabbins,1 and I.S. Grills1; 1Department of Radiation Oncology, Beaumont Cancer Institute, Oakland University William Beaumont School of Medicine, Royal Oak, MI, 2Department of Surgery, Beaumont Cancer Institute, Oakland University William Beaumont School of Medicine, Royal Oak, MI

213 Three-Dimensional Conformal External Beam Accelerated Partial Breast Irradiation (3D-APBI): Results of a Phase I Dose Escalation Study A.G. Taghian,1 M. Ancukiewicz,1 B. Smith,1 S. MacDonald,1 M. Specht,1 A. Levy,2 A. Hirsch,3 L. Kachnic,3 S. Powell,4 and A. Recht5; 1 Massachusetts General Hospital, Boston, MA, 2Gustave Roussy Institute, Paris, France, 3Boston Medical Center, Boston, MA, 4Memorial SloanKettering Cancer Center, New York, NY, 5Beth Israel Deaconess Medical Center, Boston, MA Purpose/Objective(s): Determine the optimal dose for patients treated with 3D-APBI using twice-daily fractions of 4 Gy. Materials/Methods: From October 2003 to September 2009, 323 patients were treated on a Phase I multi-institutional IRB-approved dose-escalation trial. All patients gave written informed consent. The prescribed doses in the three cohorts were 32 Gy (98 pts), 36 Gy (100 pts), and 40 Gy (125 pts). Eligibility criteria included: tumor 2 cm or smaller; infiltrating ductal histology or special subtype; pN0; no EIC or LVI; margins 2 mm or wider. Patients with DCIS grade 1 or 2 were eligible for the second and third cohorts. The excision cavity was expanded by 1.5-2 cm to create the planning target volume (PTV), which was then edited to