Validation study of the UICC TNM classification of malignant tumors, seventh edition, in breast cancer.

Background: The TNM classification of the Unio Internationalis Contra Cancrum was revised for the seventh edition. The major change concerning breast cancer is a change in the stages for patients with T0 or T1N1miM0. In the present study, the seventh edition of the TNM classification was validated in breast cancer.

Methods: The stages of 416 breast cancer patients, treated at our hospital in 1996, were classified according to the TNM classification, sixth and seventh editions, and their prognoses were compared.

Results: Case distribution using the sixth edition was stage 0, 56 cases (13.5 %); stage I, 158 cases (38.0 %); stage II, 130 [A, 102; B, 28] cases (31.2 [A, 24.5; B, 6.7] %); and stage III, 72 [A, 31; B, 8; C, 33] cases (17.3 [A, 7.5; B, 1.9; C, 7.9] %). According to the seventh edition, the stages for 20 patients, accounting for 19.6 % of IIA cases according to the sixth edition, decreased from IIA to IB. The 10-year overall survivals were stage 0, 91.1 %; stage I, 88.6 %; stage II, 80.8 %; and stage III, 63.9 % according to the sixth edition; and stage 0, 91.1 %; stage I, 88.8 %; stage II, 79.1 %; and stage III, 63.9 % according to the seventh edition. Although no significant differences were seen among the survival rates for stages 0 to II according to the sixth edition, there was a significant difference between stage I and II according to the seventh edition (p = 0.026).

Conclusion: The latest revision of the TNM classification is appropriate for breast cancer from the perspective of prognosis.