An online programme used to predict suitable treatments for breast cancer has underestimated the death rate of women under 40 from the disease by 25%, a study has found.
The study carried out an evaluation of the PREDICT programme which was developed after studying thousands of UK women of all ages, published in the British Journal of Cancer.
While overall it is accurate, the accuracy rates among younger women, less than 5% of all breast cancer cases, might have been affected by small sample size when the programme was developed.
The researchers used information from 3000 breast cancer patients and found 610 deaths occurred compared to the 610 which were predicted.
For ER positive cases PREDICT underestimated the number of deaths within five years by 56% with 360 actual to 160 predicted.
In ER negative cases PREDICT overestimated the number of deaths by 21%, about with 250 actual compared to about 300 predicted.
Longer-term estimates were found to be more accurate for those who would die within eight to ten years of diagnosis were more accurate, though the pattern for ER positive and negative persisted.
Professor Diana Eccles co-author of the Evaluation said: "This research emphasises growing understanding that breast cancer in young women can behave differently, so making predictions using information from mainly older women may not always be accurate enough for younger patients and doctors trying to make important decisions about treatment.
"The computer programme was developed using information from breast cancer patients of all ages, but included data from only a small number of very young women.
"This could explain why it isn't as accurate as we would like for younger patients. Our findings will be used to help the group in Cambridge to develop the software further, giving more accurate estimates for younger women."
Martin Ledwick, head information nurse at Cancer Research UK said: "Computer programmes like PREDICT add to the information that doctors and women have when agreeing on treatment, which might be hormone therapy, chemotherapy or surgery.
"This evaluation had limitations but it provides valuable data to help improve PREDICT's accuracy for younger women."
