Abstract
A prospective 5βyear clinical trial was conducted by the National Cancer Institute of Canada to assess the TNM classification for breast cancer proposed by the International Union Against Cancer (UICC). The study period was 1960β1964 with a 5βyear followβup on all cases. Excluding those with distant metastases (59), lost to followβup (14), and incomplete data (97) there are 1,347 cases in the study. The clinical data recorded covered the size of the primary tumour and involvement of skin and underlying structures. Tumours less than 5 cm in diameter but with varying degrees of nodal involvement accounted for 66.1% of the total while 56.6% had no palpable axillary nodes. Only 1.4% of all cases had clinical evidence of involvement of supraclavicular or infraβclavicular nodes. These proportions are significantly different from those reported for retrospective studies. This study shows that the survived of patients is related to the size of the tumour, the presence of skin fixation and the degree of nodal involvement. There does not appear to be a relationship with involvement of the pectoral muscle. The determination of whether or not involved axillary nodes contain growth is difficultβ the study shows that 39.1% of cases with no palpable nodes had positive histology. The survival rate for certain categories of cases did not fit the stage groupings proposed by the UICC and possible explanations for these variations are presented. No relationship could be found between involvement of the pectoral muscle, based on clinical assessment, and prognosis.