A comparison of the biological and clinical features of invasive lobular and ductal carcinomas of the breast.

Altogether 295 consecutive pure lobular invasive breast cancers diagnosed between 1990 and 1999 in the area of Tampere University Hospital were compared to 295 ductal invasive breast cancers. Biological factors, DFS, OS, recurrence types, survival after recurrence and other primary cancers were analyzed. ILC tumors were more often hormone receptor-positive, slowly proliferative and Erbb-2-negative. During the mean follow-up time of 5.1 years 76 recurrences in both groups were discovered. During the whole follow-up time there was more metastation to gynecological organs and GI tract in the ILC group. Bilateral breast cancers did not differ between the groups. DFS and OS were the same between the groups despite the fact that ILC patients received statistically significantly less adjuvant treatment. In conclusion, since ILC cancers are more often hormone receptor-positive, there is a good option to adjuvant endocrine therapy with present and future preparations, this possibly leading to improvement in OS.