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Response to radiotherapy after breast-conserving surgery in different breast cancer subtypes in the Swedish Breast Cancer Group 91 radiotherapy randomized clinical trial

Sjöström, Martin LU ; Lundstedt, Dan; Hartman, Linda LU ; Holmberg, Erik; Killander, Fredrika LU ; Kovács, Anikó; Malmström, Per LU ; Niméus, Emma LU ; Rönnerman, Elisabeth Werner and Fernö, Mårten LU , et al. (2017) In Journal of Clinical Oncology 35(28). p.3222-3229
Abstract

Purpose: To evaluate the effect of adjuvant radiotherapy (RT) after breast conservation surgery in different breast cancer subtypes in a large, randomized clinical trial with long-term follow-up. Patients and Methods: Tumor tissue was collected from 1,003 patients with node-negative, stage I and II breast cancer who were randomly assigned in the Swedish Breast Cancer Group 91 Radiotherapy trial between 1991 and 1997 to breast conservation surgery with or without RT. Systemic adjuvant treatment was sparsely used (8%). Subtyping was performed with immunohistochemistry and in situ hybridization on tissue microarrays for 958 tumors. Results: RT reduced the cumulative... (More)

Purpose: To evaluate the effect of adjuvant radiotherapy (RT) after breast conservation surgery in different breast cancer subtypes in a large, randomized clinical trial with long-term follow-up. Patients and Methods: Tumor tissue was collected from 1,003 patients with node-negative, stage I and II breast cancer who were randomly assigned in the Swedish Breast Cancer Group 91 Radiotherapy trial between 1991 and 1997 to breast conservation surgery with or without RT. Systemic adjuvant treatment was sparsely used (8%). Subtyping was performed with immunohistochemistry and in situ hybridization on tissue microarrays for 958 tumors. Results: RT reduced the cumulative incidence of ipsilateral breast tumor recurrence (IBTR) as a first event within 10 years for luminal A–like tumors (19% v 9%; P = .001), luminal B–like tumors (24% v 8%; P, .001), and triple-negative tumors (21% v 6%; P = .08), but not for human epidermal growth factor receptor 2–positive (luminal and nonluminal) tumors (15% v 19%; P = .6); however, evidence of an overall difference in RT effect between subtypes was weak (P = .21). RT reduced the rate of death from breast cancer (BCD) for triple-negative tumors (hazard ratio, 0.35; P = .06), but not for other subtypes. Death from any cause was not improved by RT in any subtype. A hypothesized clinical low-risk group did not have a low risk of IBTR without RT, and RT reduced the rate of IBTR as a first event after 10 years (20% v 6%; P = .008), but had no effect on BCD or death from any cause. Conclusion: Subtype was not predictive of response to RT, although, in our study, human epidermal growth factor receptor 2–positive tumors seemed to be most radioresistant, whereas triple-negative tumors had the largest effect on BCD. The effect of RT in the presumed low-risk luminal A–like tumors was excellent.

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Journal of Clinical Oncology
volume
35
issue
28
pages
8 pages
publisher
American Society of Clinical Oncology
external identifiers
  • scopus:85030221562
  • wos:000411862300008
ISSN
0732-183X
DOI
10.1200/JCO.2017.72.7263
language
English
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yes
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d73301f9-d447-403c-9b00-d7acec85415c
date added to LUP
2017-10-24 15:48:24
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2018-01-16 13:23:55
@article{d73301f9-d447-403c-9b00-d7acec85415c,
  abstract     = {<p>Purpose: To evaluate the effect of adjuvant radiotherapy (RT) after breast conservation      surgery      in different breast cancer subtypes in a large, randomized clinical trial      with      long-term follow-up. Patients and Methods: Tumor tissue was collected from 1,003      patients      with node-negative, stage I and II breast cancer who were randomly assigned      in      the Swedish Breast Cancer Group 91 Radiotherapy trial between 1991 and 1997 to      breast      conservation surgery with or without RT. Systemic adjuvant treatment was sparsely      used      (8%). Subtyping was performed with immunohistochemistry and in situ hybridization      on      tissue microarrays for 958 tumors. Results: RT reduced the cumulative incidence      of      ipsilateral breast tumor recurrence (IBTR) as a first event within 10 years for      luminal      A–like tumors (19% v 9%; P = .001), luminal B–like tumors (24% v 8%; P, .001),      and      triple-negative tumors (21% v 6%; P = .08), but not for human epidermal growth      factor      receptor 2–positive (luminal and nonluminal) tumors (15% v 19%; P = .6); however,      evidence      of an overall difference in RT effect between subtypes was weak (P = .21).      RT      reduced the rate of death from breast cancer (BCD) for triple-negative tumors      (hazard      ratio, 0.35; P = .06), but not for other subtypes. Death from any cause was      not      improved by RT in any subtype. A hypothesized clinical low-risk group did not      have      a low risk of IBTR without RT, and RT reduced the rate of IBTR as a first event      after      10 years (20% v 6%; P = .008), but had no effect on BCD or death from any cause.      Conclusion:      Subtype was not predictive of response to RT, although, in our study,      human      epidermal growth factor receptor 2–positive tumors seemed to be most radioresistant,      whereas      triple-negative tumors had the largest effect on BCD. The effect of RT in      the      presumed low-risk luminal A–like tumors was excellent.</p>},
  author       = {Sjöström, Martin and Lundstedt, Dan and Hartman, Linda and Holmberg, Erik and Killander, Fredrika and Kovács, Anikó and Malmström, Per and Niméus, Emma and Rönnerman, Elisabeth Werner and Fernö, Mårten and Karlsson, Per},
  issn         = {0732-183X},
  language     = {eng},
  month        = {10},
  number       = {28},
  pages        = {3222--3229},
  publisher    = {American Society of Clinical Oncology},
  series       = {Journal of Clinical Oncology},
  title        = {Response to radiotherapy after breast-conserving surgery in different breast cancer subtypes in the Swedish Breast Cancer Group 91 radiotherapy randomized clinical trial},
  url          = {http://dx.doi.org/10.1200/JCO.2017.72.7263},
  volume       = {35},
  year         = {2017},
}