| Objective: The aim of this study was to investigate the prognostic effect of postmastectomy radiotherapy in early breast cancer patients of T1-2N1M0 treated with modified radical mastectomy,and to analyze the prognostic effect of postmastectomy radiotherapy in different molecular subtypes of breast cancer patients.Methods: Four hundred and eighty-four early breast cancer patients of T1-2N1M0 treated with modified radical mastectomy were retrospectively analyzed from January 2006 to October 2010 in the Second Affiliated Hospital of Dalian Medical University.Analysis of the 5-year locoregional recurrence rate(LRR),distant metastasis rate(DM),recurrence free survival(RFS),and overall survival rate(OS)in the whole group,univariate and multivariate analysis of prognostic factors such as age,menstruation status,tumor size et al,investigating the value of postmastectomy radiotherapy,and analyzing the effects of postmastectomy radiotherapy on the Luminal A,Luminal B,over expression of Her-2 and triple-negative breast cancer for 5-year LRR,DM,RFS and OS were performed.Results:1.The follow-up time was 20-121 months and the median follow-up time was 66 months.The follow-up rate was 84.9%.The 5-year LRR was 11.6%,DM was 20%,RFS was 74.6%,OS was 92.4% in the whole group of patients.2.Univariate analysis of prognostic factors(1)Factors for LRR: tumor size(?~2=4.789,P=0.029),the total number of lymph node dissection(?~2=15.446,P=0.000),lymph node positive ratio(?~2=7.911,P=0.005),histological grade(?~2=9.649,P=0.022),molecular subtypes(?~2=7.873,P=0.049),radiotherapy or not(?~2=17.607,P=0.000)were the risk factors for 5-year LRR.(2)Factors for DM: age(?~2=7.179,P=0.028),menstruation status(?~2=8.912,P=0.003),tumor size(?~2=5.977,P=0.014),the total number of lymph node dissection(?~2=9.833,P=0.002),lymph node positive ratio(?~2=4.883,P=0.027),histological grade(?~2=10.695,P=0.013),molecular subtypes(?~2=11.726,P=0.008),radiotherapy or not(?~2=6.854,P=0.009)were the risk factors for 5-year DM.(3)Factors for RFS: menstruation status(?~2=7.326,P=0.007),tumor size(?~2=4.539,P=0.033),the total number of lymph node dissection(?~2=10.454,P=0.001),lymph node positive ratio(?~2=5.074,P=0.024),histological grade(?~2=10.836,P=0.013),molecular subtypes(?~2=11.248,P=0.010),radiotherapy or not(?~2=16.324,P=0.000)were the risk factors for 5-year RFS.(4)Factors for OS: tumor size(?~2=4.688,P=0.030),the number of positive lymph nodes(?~2=10.681,P=0.005),molecular subtypes(?~2=28.869,P=0.000)were the risk factors for 5-year OS.3.Multivariate analysis of prognostic factorsLymph node positive ratio(?~2=3.936,P=0.047,HR=2.242,95%CI 1.010-4.976),histological grade(?~2=4.054,P=0.044,HR=1.432,95%CI 1.010-2.032),radiotherapy or not(?~2=8.481,P=0.004,HR=0.363,95%CI 0.183-0.718)were the independent prognostic factors for 5-year LRR.Histological grade(?~2=4.582,P=0.032,HR=1.377,95%CI 1.027-1.846),molecular subtypes(?~2=9.357,P=0.002,HR=1.408,95%CI 1.131-1.754)were the independent prognostic factors for 5-year DM.Molecular subtypes(?~2=5.984,P=0.014,HR=1.277,95%CI 1.050-1.554)and lymph node positive ratio(?~2=3.939,P=0.047,HR=1.768,95%CI 1.007-3.103)were the independent prognostic factors for 5-year RFS.Molecular subtypes(?~2=7.725,P=0.005,HR=4.142,95%CI 1.520-11.282)was the only independent prognostic factor for 5-year OS.4.Prognostic effect of postmastectomy radiotherapy in different molecular 6 subtypes of breast cancer patients(1)In patients with Luminal A subtype: The 5-year LRR was 5.2%vs14.2% respectively(radiotherapy vs no radiotherapy)with a statistically significant difference(?~2=6.230,P=0.013).The 5-year RFS was 83.6%vs72.3% respectively with a statistically significant difference(?~2=5.030,P=0.025).The 5-year DM was 14.2%vs19.2%,5-year OS was 97.8%vs96.5%,both with no significant difference(?~2=1.218,P=0.270;?~2=0.416,P=0.519).(2)In patients with Luminal B subtype: The 5-year LRR was 2.1%vs14.3% respectively(radiotherapy vs no radiotherapy)with a statistically significant difference(?~2=4.373,P=0.037).The 5-year RFS was 89.4%vs65.7% respectively with a statistically significant difference(?~2=6.826,P=0.009).The 5-year OS was 97.9%vs85.7% with a statistically significant difference(?~2=4.373,P=0.037).The 5-year DM was 10.6%vs22.9%,with no significant difference(?~2=2.245,P=0.134).(3)In patients with Her-2+ subtype: The 5-year LRR was 8.6%vs30.0% respectively(radiotherapy vs no radiotherapy)with a statistically significant difference(?~2=4.270,P=0.039).The 5-year RFS was 80.0%vs55.0% respectively with a statistically significant difference(?~2=3.856,P=0.050).The 5-year DM was 17.1%vs40.0%,5-year OS was 88.6%vs75.0%,both with no significant difference(?~2=3.504,P=0.061;?~2=1.713,P=0.191).(4)In patients with triple-negative subtype: The 5-year LRR was 9.8%vs32.3% respectively(radiotherapy vs no radiotherapy)with a statistically significant difference(?~2=5.706,P=0.017).The 5-year RFS was 70.7%vs45.2% respectively with a statistically significant difference(?~2=4.798,P=0.028).The 5-year DM was 24.4%vs45.2%,5-year OS was 85.4%vs74.2%,both with no significant difference(?~2=3.427,P=0.064;?~2=1.407,P=0.236).Conclusions:1.Lymph node positive ratio,histological grade and radiotherapy or not were the independent prognostic factors for the 5-year LRR in early breast cancer patients with stage T1-2N1M0 treated with modified radical mastectomy.Histological grade and molecular subtype were independent prognostic factors for the 5-year DM.Lymph node positive ratio and molecular subtype were independent prognostic factors for the 5-year RFS.Molecular subtype was the only independent prognostic factor for the 5-year OS.2.For patients with stage T1-2N1M0 treated with modified radical mastectomy,postmastectomy radiotherapy can decrease the 5-year LRR,but had no influences on the 5-year DM,RFS and OS.Radiotherapy should be considered especially in patients with positive lymph node ratio?20% and high histological grade.3.For patients with different molecular subtypes with stage T1-2N1M0 treated with modified radical mastectomy,the 5-year LRR and RFS but not DM can benefit from postmastectomy radiotherapy to some extent.For the 5-year OS,only patients with Luminal B subtype can benefit from radiotherapy. |
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