Abstract
We have found that in setting the total lactation period of vivipara we can use its square root as its measure and produce normal distribution in our frequency distributions regarding breast cancer patients and controls.
Both in urban and rural districts, the s. r. m. means of total lactation periods for the breast cancer patients with no mastitis history and those for the controls show no noticeable difference in the groups under 45 years of age, but those for the patients stnad smaller than those for the controls in the groups over 45 years of age.
According to our data, of the total number of breast cancer patients, 16.7% is covered by those with mastitis history. There is an observed trend that the s. r. m. means of total lactation periods for the breast cancer patients with mastitis history stand large as compared with those for the patients with no mastitis history.
