Sector resection with or without postoperative radiotherapy for stage I breast cancer: 20-year results of a randomized trial.
OBJECTIVE
To investigate how radiotherapy (XRT) adds to tumor control using a standardized surgical technique with meticulous control of surgical margins in a randomized trial with 20 years of follow-up.


METHODS
Three hundred eighty-one women with pT1N0 breast cancer were randomly assigned to sector resection with (XRT group) or without (non-XRT group) postoperative radiotherapy to the breast. With follow-up through 2010, we estimated cumulative proportion of recurrence, breast cancer death, and all-cause mortality.


RESULTS
The cumulative probability of a first breast cancer event of any type after 20 years was 30.9% in the XRT group and 45.1% in the non-XRT group (hazard ratio [HR], 0.58; 95% CI, 0.41 to 0.82). The benefit of radiotherapy was achieved within the first 5 years. After 20 years, 50.4% of the women in the XRT group died compared with 54.0% in the non-XRT group (HR, 0.92; 95% CI, 0.71 to 1.19). The cumulative probability of contralateral cancer or death as a result of cancer other than breast cancer was 27.1% in the XRT group and 24.9% in the non-XRT group (HR, 1.17; 95% CI, 0.77 to 1.77). In an anticipated low-risk group, the cumulative incidence of first breast cancer of any type was 24.8% in the XRT group and 36.1% in the non-XRT group (HR, 0.61; 95% CI, 0.35 to 1.07).


CONCLUSIONS
Radiotherapy protects against recurrences during the first 5 years of follow-up, indicating that XRT mainly eradicates undetected cancer foci present at primary treatment. The similar rate of recurrences beyond 5 years in the two groups indicates that late recurrences are new tumors. There are subgroups with clinically relevant differences in risk.
Åsa Wickberg, Anders Magnuson, Kenneth Villman, Göran Liljegren, Örebro University Hospital, Örebro; Lars Holmberg, Uppsala University, Uppsala; Hans-Olov Adami, Karolinska Institutet, Stockholm, Sweden; Lars Holmberg, King's College, London, United Kingdom; Hans-Olov Adami, Harvard School of Public Health, Boston, MA.
Asa
A
Wickberg
Lars
L
Holmberg
Hans-Olov
HO
Adami
Anders
A
Magnuson
Kenneth
K
Villman
Göran
G
Liljegren
D000368:Aged; D001943:Breast Neoplasms / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D008408:Mastectomy / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000517:prevention & control*; D009367:Neoplasm Staging; D018365:Neoplasm, Residual; D016016:Proportional Hazards Models; D018714:Radiotherapy, Adjuvant; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors; D016896:Treatment Outcome