Dosimetric Comparison of Left-sided Whole Breast Irradiation with 3DCRT, Segmental IMRT, Helical Tomotherapy, Topotherapy, and IMPT

I. J. Radiation Oncology d Biology d Physics

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Volume 75, Number 3, Supplement, 2009

Patterns of Care Study of Breast Conserving Therapy in Japan: The Changes of the Treatment Process among Three Surveys

C. Yamauchi1,2, N. Shikama3,2, M. Yasunaga4,2, T. Teshima4,2, M. Mitsumori1,5 1

Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine, Kyoto, Japan, Japanese Patterns of Care Study of Working Subgroup of Breast Cancer, Osaka, Japan, 3Department of Radiology, Shinshu University, School of Medicine, Matsumoto, Japan, 4Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Osaka, Japan, 5Japanese Patterns of Care Study of Working Subgroup of Breast Cancer, Kyoto, Japan 2

Purpose/Objective(s): The Japan Patterns of Care Study (JPCS) conducted three consecutive national surveys to identify changes associated with the treatment process for the patients undergoing breast-conserving therapy (BCT) for early breast cancer. The purpose of this study is to compare the results among the three national surveys. Materials/Methods: Hospitals and patients were selected using a two-stage cluster sampling method, and external audits were conducted by radiation oncologists. The third survey (JPCS3) collected the data of 610 patients underwent BCT between 2003 and 2005 and comparison was made with previous two surveys (JPCS1: 865 patients treated between 1995-1997, JPCS2: 746 patients treated between 1999-2001). Results: The median age of the patients was significantly increased among three surveys and the median age was 49.2, 52.4 and 53.5 in JPCS1, JPCS2 and JPCS3, respectively (p\0.0001). Although there was a significant reduction in the extent of breast surgery and less patients received quadrantectomy in JPCS2 (30.3%) compared with JPCS1 (57.0%), there was not significant change in JPCS3 (26.7%) compared with JPCS2. Sentinel lymph node biopsy (SLNB) was performed for 12.2% of the patients in the JPCS-2 and 34.7% in JPCS3. As concern with treatment planning, fixation system such as cast or shell was used on 69.8% of the patients in JPCS3 and the rate was significantly higher than those of the JPCS1(32.6%) and the JPCS2(52.9%). CT simulation was increasingly used for 65.9% of the JPCS3, although it was used for only 22.2% of the JPCS1 cases and 26.7% of the JPCS2. Breast irradiation was given predominantly with photons of #6MV in the JPCS2 (91.3%) and the JPCS3 (96.3%) compared to JPCS1(73.3%) (p\0.001). Photon of $ 10MV without bolus, which is inappropriate for small breast, was used on up to 4.4% of the patients in the JPCS1, 2.0% in the JPCS2.and 1.1% in the JPCS3. Matching of the dorsal margin of tangential fields was performed for 96.3% of the JPCS3 cases, although it was performed for only 78.8% of the JPCS1 cases and 85.0% of the JPCS2 cases. Conclusions: The three surveys demonstrated changes of the trend in the treatment process of BCT in Japan. Techniques of radiation therapy were significantly improved. The treatment guideline for BCT published by Japanese Breast Cancer Society in 1999 seems to have an impact on the patterns of care in Japan, considering the rapid changes that have taken place within this period. Author Disclosure: C. Yamauchi, None; N. Shikama, None; M. Yasunaga, None; T. Teshima, None; M. Mitsumori, None.

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Comparison of Displacement between Free Breath and Active Breath Control Condition Measured by Electronic Portal Imaging Device in Breast Radiotherapy

M. Xu, J. Li, Y. Han, X. Wang, T. Liu Shandong Tumor Hospital, Jinan, China Purpose/Objective(s): To measure the displacement respectively in condition of free breath (FB) and active breathing control using electronic portal imaging device (EPID) and compare the difference of the displacement between FB and ABC for the patients treated by intensity-modulated radiotherapy (IMRT). Materials/Methods: Twenty nine breast cancer patients receiving IMRT after breast-conserving surgery were enrolled in the study, sixteen patients received radiotherapy in condition of FB (FB group) and thirteen patients at state of ABC (ABC group). Electronic portal imaging (EPI) was performed for all patients in FB group and ABC group before each irradiation at the position of the two main tangential fields, and EPI was performed twice in 8 patients in ABC group before each irradiation. The digital reconstructed radiograph (DRR) derived from CT simulation image was used as referred image, the EPI image was manually matched with DRR according to the chest wall and breast profile, and the displacement in vertical and horizontal direction were measured. Results: A total of 504 EPI images were obtained, 253 images in FB group, 251images in ABC group. The mean displacement in FB group were 1.93mm and 0.99mm in horizontal and vertical directions respectively, and the mean displacement in ABC group were 1.97mm and 1.14mm in horizontal and vertical directions respectively, and the number of displacements in excess of 5mm were not more than 4%. The difference of the displacement between the FB and ABC group in both horizontal and vertical directions were not statistically significant (p = 0.778 and p = 0.142). For the 8 patients who received twice EPI before each irradiation in ABC group, the difference of the displacements derived respectively from first and second EPI was not statistically significant in both horizontal and vertical direction (p = 0.220 and p = 0.862). Conclusions: Although active breathing control can reduce the degree of motion of the breast in theory, the active breathing control has no superiority in reducing the displacement derived from the mixture of set-up error and respiratory motion in breast radiotherapy. Performance of EPI before each irradiation is requisite in breast radiotherapy assisted by ABC to correct the set-up error and threshold of the moderately deep inspiratory hold. It is rational to extend margin of 5mm for irradiation of the breast from CTV to PTV. Author Disclosure: M. Xu, None; J. Li, None; Y. Han, None; X. Wang, None; T. Liu, None.

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Dosimetric Comparison of Left-sided Whole Breast Irradiation with 3DCRT, Segmental IMRT, Helical Tomotherapy, Topotherapy, and IMPT

E. R. Sengbusch, L. K. Schubert, D. C. Westerly, V. Gondi, G. Krey, E. T. Soisson, W. A. Tome´, R. R. Patel, T. R. Mackie, G. M. Cannon University of Wisconsin School of Medicine and Public Health, Madison, WI Purpose/Objective(s): To compare dose distributions obtained with 3D-conformal radiotherapy (3DCRT), segmental IMRT, helical tomotherapy (HT), topotherapy (topo), and intensity modulated proton radiotherapy (IMPT) for patients with left-sided breast cancer.

Proceedings of the 51st Annual ASTRO Meeting Materials/Methods: Treatment plans were created for 10 patients with left-sided breast cancer. The PTV enveloped the entire breast with a 7 mm setup margin. A retracted PTV (rPTV) was created by subtracting 5 mm from the superficial PTV border to negate variations in superficial dose distributions between treatment modalities and planning systems. 3DCRT used standard tangents. IMRT plans used standard tangents with 1-3 additional forward planned field-in-field segments. HT plans used complete blocking of the contralateral breast and lung and directional blocking of the heart and spinal cord. Topo plans used two tangent beam angles with directional blocking of the heart. IMPT plans used a 2-field spot scanning technique. Plans were normalized to a prescription of 50 Gy (2 Gy/fx) to 98% of the rPTV. Coverage and homogeneity metrics for the rPTV and dose volume metrics for normal tissues were compared with multiple comparison tests using critical values from the t distribution with the Bonferroni adjustment and an upper bound of p\0.05. Results: Homogeneity index was improved (p \ 0.0001) for IMPT (0.0458), topo (0.0491), and HT (0.0562) versus IMRT (0.141) and 3DCRT (0.146). The prescription isodose to target volume ratio was improved (p \ 0.01) for IMPT (1.244) versus the other four modalities (1.496-1.698). Heart mean dose was lower (p \ 0.001) for IMPT (0.133 Gy) versus topo (1.94 Gy), IMRT (2.09 Gy), and 3DCRT (2.64 Gy), which were lower (p\0.05) than HT (3.92 Gy). Heart max dose was lower (p \ 0.005) for IMPT (26.8 Gy) and HT (34.1 Gy) versus topo (46.3 Gy), IMRT (50.2 Gy), and 3DCRT (52.4 Gy). Left lung mean dose was lower (p \ 0.02) for IMPT (3.91 Gy) versus topo (6.58 Gy), IMRT (7.85 Gy), and 3DCRT (8.35 Gy), which were lower (p\0.001) than HT (11.8 Gy). Right lung mean was lower (p \ 0.0005) for IMPT (\0.001 Gy), IMRT (0.071 Gy), and 3DCRT (0.114 Gy) versus topo (0.327 Gy), which was lower (p \ 0.003) than HT (0.613 Gy). Right breast mean dose was lower (p \ 0.05) for IMPT (\0.001 Gy) versus IMRT (0.199 Gy) and 3DCRT (0.298 Gy), which were lower (p \ 0.05) than topo (0.497 Gy) and HT (0.595 Gy). Conclusions: HT, topo, and IMPT display similar target coverage and homogeneity, and are superior in these metrics to 3DCRT and IMRT. IMPT improves target conformation while also significantly reducing dose to all relevant normal structures. Improving PTV coverage with HT comes at the expense of increased normal tissue mean doses. Topo provides target coverage similar to that achieved by HT with lower normal tissue mean doses. Author Disclosure: E.R. Sengbusch, None; L.K. Schubert, None; D.C. Westerly, None; V. Gondi, None; G. Krey, None; E.T. Soisson, None; W.A. Tome´, None; R.R. Patel, None; T.R. Mackie, T.R. Mackie has financial interest in TomoTherapy, Inc., E. Ownership Interest; G.M. Cannon, None.

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Prognostic Value of P53 Expression in Patients Treated with Breast Conserving Therapy

A. Rewari1, S. Goyal1, N. Taunk1, H. Wu1, M. Moran2, B. Haffty1 1

UMDNJ - Cancer Institute of New Jersey, New Brunswick, NJ, 2Yale University School of Medicine, New Haven, CT

Purpose/Objective(s): The p53 tumor suppressor gene encodes a nuclear phosphoprotein that is important in cell cycle regulation, DNA repair, and induction of apoptosis by ionizing radiation. Several studies have demonstrated a relationship between the nuclear accumulation of p53 protein (a surrogate marker of p53 inactivation) and poor disease-free and overall survival in locally advanced breast cancer patients treated with mastectomy or hormonal therapy. Less clear is the role of p53 as a biologic predictor of response to radiotherapy in early stage breast cancer patients. The purpose of this study was to investigate the prognostic value of p53 in early-stage breast cancer patients who were treated with breast conserving therapy (BCT). Materials/Methods: Paraffin specimens from 452 patients with early stage breast cancer treated with BCT were constructed into tissue micro-arrays. Accumulation of p53 protein was evaluated by immunohistochemistry with less than 10% nuclear staining scored as negative and greater than 10% nuclear staining scored as positive. This was then correlated with clinico-pathologic factors and outcomes data. Results: Nuclear accumulation of p53 protein was noted in 31% of tumor specimens. Overexpression of p53 protein was found to be correlated with estrogen receptor (ER) negativity (p = 0.006), progesterone receptor (PR) negativity (p = 0.005), Her-2/neu expression (p = 0.03), African Americans (p = 0.0001), and reduced use of adjuvant chemotherapy (p = 0.0003). In univariate analysis, p53 expression was not correlated with local-regional recurrence (LR), distant metastases (DM), breast-cancer specific survival (BCSS), and overall survival (OS). On subset analysis of ER/PR negative, Her-2/neu positive, and African American patients, there was no association between p53 expression and LR, DM, BCSS, or OS. Conclusions: Nuclear accumulation of p53 did not predict for outcomes in early-stage breast cancer patients treated with BCT. p53 overexpression was correlated with worsening prognostic indicators such as ER/PR negativity, Her-2/neu expression, and African Americans. To our knowledge, this is the largest study to evaluate the role of p53 as a biologic predictor of response to radiotherapy in early-stage breast cancer patients. Author Disclosure: A. Rewari, None; S. Goyal, None; N. Taunk, None; H. Wu, None; M. Moran, None; B. Haffty, None.

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Interstitial High Dose Rate (HDR) Brachytherapy for Early Stage Breast Cancer: Median 6 Year Followup of 214 Cases using Multi-catheter Technique

P. J. Anderson1, R. J. Mark1,2, R. S. Akins1, M. Nair1 1

Joe Arrington Cancer Center, Lubbock, TX, 2Texas Tech University, Lubbock, TX

Purpose/Objective(s): External Beam Radiation Therapy (EBRT) has been the standard of care for breast conservation radiation therapy. Recent data indicates that Interstitial Implant and High Dose Rate (HDR) radiation afterloading compares very favorably to EBRT in selected patients. Materials/Methods: Patients with Tis, T1, and T2 tumors measuring # 4 cm, negative surgical margins, and # 3 axillary lymph nodes were judged to be candidates for Interstitial Implant. Implants were performed under Stereotactic Mammographic guidance with conscious sedation and local anesthesia. The implants were placed with a custom designed template using from 3 to 8 planes, and 8 to 62 needles. Catheters were subsequently threaded thru the needles, and the needles removed. Catheter spacing was 1.0 to 1.5 cm. Radiation Treatment planning was performed using CT Scanning and the Plato System. Treatment volumes ranged from 25

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