Changes in surgical treatments: the example of hysterectomy versus conization for cervical carcinoma in situ. From 1969 through 1985, 4584 women in the state of New Mexico were diagnosed with carcinoma in situ of the cervix. Of these women, 65.5% underwent hysterectomy while 31.1% had a conservative therapy (primarily conization). Over the 17-year period, there was a steady increase in the percentage of women receiving conservative therapies, from 11.8% in 1969 to 50.3% in 1985. Younger women, unmarried women and American Indian women were more likely to receive conservative therapy. This marked shift in therapeutic approach occurred during a time of apparent controversy as to the optimal treatment for cervical carcinoma in situ, and illustrates a rapid change in surgical practice in the absence of any controlled trials comparing the two major treatment modalities. 