Pathologists studying breast cancer biopsies calculate the mitotic index to determine the tumor's grade and rate of proliferation.
The formula for the mitotic index is:
mitotic index=number of cells undergoing mitosistotal number of cells×100 \text{mitotic index} = \frac{\text{number of cells undergoing mitosis}}{\text{total number of cells}} \times 100 mitotic index=total number of cellsnumber of cells undergoing mitosis×100A pathologist examines a stained biopsy slide under a microscope and counts 18 cells actively undergoing mitosis and 222 cells in interphase (not undergoing mitosis). Calculate the mitotic index for this biopsy sample.
In a biopsy from another patient, the pathologist calculates a mitotic index of 12.5%12.5\%12.5%. If the total number of cells counted across the field of view was 560, calculate the number of cells that were undergoing mitosis.
Explain one difficulty a pathologist might face when trying to accurately count cells to calculate the mitotic index from a tissue biopsy slide.
