No long-term increase in cardiac-related mortality after breast-conserving surgery and radiation therapy using modern techniques.
OBJECTIVE
To determine whether left-breast irradiation using modern techniques after breast-conserving surgery leads to an increased risk of cardiac-related mortality.


METHODS
Between 1968 and 1986, 1,624 patients were treated for unilateral stage I or II breast cancer at the Joint Center for Radiation Therapy, Harvard Medical School, Boston, MA, with conservative surgery and breast irradiation. Seven hundred forty-five patients with a potential follow-up of at least 12 years were analyzed. Clinical, pathologic, and treatment characteristics were compared between the 365 patients (49%) who received left-sided irradiation and the 380 patients (51%) who received right-sided irradiation. The relationship between left-sided breast irradiation and the risk of nonbreast cancer- and cardiac-related mortality was examined.


RESULTS
There was no significant difference in the distribution of clinical, pathologic, or treatment characteristics between the two groups, with the exception of a small difference in pathologic tumor size (medians, left, 2.0 cm, right, 1.5 cm; P = .007). At 12 years, a majority of patients still were alive. Slightly more patients with left-sided tumors had died of breast cancer (31% v 27%; P = NS). Equivalent proportions from each group died of nonbreast cancer causes (11%), including nine patients (2%) from each group who died from cardiac causes. The risk of cardiac mortality did not increase as time after treatment increased for patients who received left-sided irradiation compared with right-sided irradiation. A model that controlled for clinical, pathologic, and treatment differences showed no significant increase in any category of cause of death (breast, cardiac, or other) for patients who received left-sided irradiation.


CONCLUSIONS
These results suggest that modern breast radiotherapy is not associated with an increased risk of cardiac-related mortality within at least the first 12 years after treatment.
Nixon
A J
AJ
Joint Center for Radiation Therapy and the Division of Biostatistics, Harvard Medical School, Boston, MA 02215, USA. anixon@bidmc.harvard.edu
Manola
J
J
Gelman
R
R
Bornstein
B
B
Abner
A
A
Hetelekidis
S
S
Recht
A
A
Harris
J R
JR
D001943:Breast Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D003131:Combined Modality Therapy; D005260:Female; D006321:Heart / Q000528:radiation effects*; D006331:Heart Diseases / Q000401:mortality*; D006801:Humans; D016015:Logistic Models; D015412:Mastectomy, Segmental; D008875:Middle Aged; D011832:Radiation Injuries / Q000401:mortality; D015996:Survival Rate; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome