Growth rates of primary breast cancers.

The growth rates of breast cancers are a critical aspect of the natural history of the disease. Growth rates of 32 primary breast cancers were determined from serial mammographic views of tumor nucleus shadows in a population of 109 cancers. These cancers were found in a screening population of 10,120 women receiving over 30,000 mammograms over 3 years. Tumor volume doubling times ranged from 109 days to 944 days with mean doubling time of 325 days in 23 cases with 9 tumors showing no growth. Additional cancers surfaced that were growing too fast to be measured. These cancers were significantly more likely to metastasize but because of the small sample size the absolute percentage of tumors in that fast growing subset was not determinable but ranged between 17 and 77% of the 109 cancers.