Bilateral implant reconstruction does not affect the quality of postmastectomy radiation therapy.
To determine if the presence of bilateral implants, in addition to other anatomic and treatment-related variables, affects coverage of the target volume and dose to the heart and lung in patients receiving postmastectomy radiation therapy (PMRT). A total of 197 consecutive women with breast cancer underwent mastectomy and immediate tissue expander (TE) placement, with or without exchange for a permanent implant (PI) before radiation therapy at our center. PMRT was delivered with 2 tangential beams + supraclavicular lymph node field (50Gy). Patients were grouped by implant number: 51% unilateral (100) and 49% bilateral (97). The planning target volume (PTV) (defined as implant + chest wall + nodes), heart, and ipsilateral lung were contoured and the following parameters were abstracted from dose-volume histogram (DVH) data: PTV D95% > 98%, Lung V20Gy > 30%, and Heart V25Gy > 5%. Univariate (UVA) and multivariate analyses (MVA) were performed to determine the association of variables with these parameters. The 2 groups were well balanced for implant type and volume, internal mammary node (IMN) treatment, and laterality. In the entire cohort, 90% had PTV D95% > 98%, indicating excellent coverage of the chest wall. Of the patients, 27% had high lung doses (V20Gy > 30%) and 16% had high heart doses (V25Gy > 5%). No significant factors were associated with suboptimal PTV coverage. On MVA, IMN treatment was found to be highly associated with high lung and heart doses (both p < 0.0001), but implant number was not (p = 0.54). In patients with bilateral implants, IMN treatment was the only predictor of dose to the contralateral implant (p = 0.001). In conclusion, bilateral implants do not compromise coverage of the target volume or increase lung and heart dose in patients receiving PMRT. The most important predictor of high lung and heart doses in patients with implant-based reconstruction, whether unilateral or bilateral, is treatment of the IMNs. Refinement of radiation techniques in reconstructed patients who require comprehensive nodal irradiation is warranted.
Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY. Electronic address: hoa1234@mskcc.org.
Alice Y
AY
Ho
Drexel University College of Medicine, Philadelphia, PA.
Nisha
N
Patel
Department of Radiation Oncology, Mount Sinai School of Medicine, New York, NY.
Nisha
N
Ohri
Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York.
Monica
M
Morrow
Department of Plastic Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY.
Babak J
BJ
Mehrara
Department of Plastic Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY.
Joseph J
JJ
Disa
Department of Plastic Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY.
Peter G
PG
Cordeiro
Department of Biostatistics and Epidemiology, Memorial Sloan-Kettering Cancer Center, New York, NY.
Weiji
W
Shi
Department of Biostatistics and Epidemiology, Memorial Sloan-Kettering Cancer Center, New York, NY.
Zhigang
Z
Zhang
Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY.
Daphna
D
Gelblum
Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY.
Claire T
CT
Nerbun
Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY.
Katherine M
KM
Woch
Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY.
Ase
A
Ballangrud
Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY.
Beryl
B
McCormick
Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY.
Simon N
SN
Powell
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018427:Breast Implants / Q000706:statistics & numerical data*; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000628:therapy*; D003131:Combined Modality Therapy / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D015994:Incidence; D008408:Mastectomy / Q000706:statistics & numerical data*; D008875:Middle Aged; D009518:New York / Q000453:epidemiology; D011832:Radiation Injuries / Q000453:epidemiology* / Q000517:prevention & control; D018714:Radiotherapy, Adjuvant / Q000706:statistics & numerical data; D020266:Radiotherapy, Conformal / Q000706:statistics & numerical data*; D012307:Risk Factors; D016896:Treatment Outcome; D055815:Young Adult
Breast cancer; Immediate reconstruction; Implant; Postmastectomy radiation