The impact of the number of excised axillary nodes and of the percentage of involved nodes on regional nodal failure in patients treated by breast-conserving surgery with or without regional irradiation.
OBJECTIVE
After breast-conserving surgery, recommendations for regional nodal radiotherapy are usually based on the number of positive nodes. This number is dependent on the number of nodes removed during the axillary dissection. This study examines whether the percentage of positive nodes may help to select patients for regional radiotherapy.


METHODS
A retrospective study was conducted on 1,372 T1-T2 node-positive breast cancer patients treated at L'Hôtel-Dieu de Québec Hospital between 1972 and 1997.


RESULTS
Among the patients who did not receive regional radiotherapy, the percentage of involved nodes was significantly associated with axillary failure. Ten-year axillary control rates were 97% and 91% when the percentage of involved nodes was <50% and > or =50%, respectively (p = 0.007). In addition, regional radiotherapy is always significantly associated with a decrease in overall regional failure (axillary and/or supraclavicular), regardless of the percentage of involved nodes. However, regional radiotherapy reduced the axillary failure rate (2% vs. 9%, p = 0.007) only when more than a specific percentage of nodes was involved (> or =40% if N1-3 and > or =50% if N>3 nodes).


CONCLUSIONS
The percentage of involved nodes should be taken into consideration in selecting patients for regional radiotherapy. Irradiation of the axilla should be reserved for patients with a specific ratio: >40% involved nodes if N1-3 and > or =50% involved nodes if N>3 nodes.
Department of Radiation Oncology, L'Hôtel-Dieu de Québec, Québec City, Québec, Canada. afortin@videotron.ca
André
A
Fortin
Anne
A
Dagnault
Lucie
L
Blondeau
Thi Trinh Thuc
TT
Vu
Marie
M
Larochelle
D000328:Adult; D001365:Axilla; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D003131:Combined Modality Therapy / Q000379:methods; D005260:Female; D006801:Humans; D008197:Lymph Node Excision / Q000379:methods*; D015182:Lymphatic Irradiation / Q000379:methods*; D008207:Lymphatic Metastasis / Q000473:pathology / Q000532:radiotherapy; D015411:Mastectomy, Modified Radical; D015412:Mastectomy, Segmental; D008875:Middle Aged; D016016:Proportional Hazards Models; D011879:Radiotherapy Dosage; D012189:Retrospective Studies