Breast parenchymal patterns: analysis of 332 incident breast carcinomas.

A detailed analysis of 332 incident breast carcinomas is presented. The study results indicate that there is validity to the breast parenchymal patterns as an indication of risk for developing breast cancer and that risk is independent of length of follow-up and age of patient. All cases were drawn from a referral-type practice at Hutzel Hospital, Detroit, MI. The cases were compared to controls for computation of relative risk up to and beyond a follow-up period of 48 months. They were also compared to a consecutive series of prevalent breast carcinomas seen at Hutzel Hospital during the 6 years 1975-1980. The extent of disease in the cases described in this report is somewhat more favorable than in a consecutive series of prevalent cancers operated on a Hutzel Hospital. Most breast cancers occur in the P2 breast, a smaller number in the DY, and only 12% in the combined N1P1 type. The conclusions of other investigators regarding parenchymal patterns as risk indicators are reviewed. Particular attention was paid to comparing the length of follow-up and age of patient. There was no diminution of proportions of cases in the P2/N1-P1 or DY/N1-P1 after a 48 month follow-up. There was a significant diminution in the proportion of cases falling into DY/N1-P1 after age 50, and less so in P2/N1-P1. Furthermore, relative risk was unaffected by time or age.