Just going to answer this and your other link to the report.
1 It is a tiny sample- 695 women.
2 These women were part of the WHI study which is discredited now.
3 The report you linked to is now almost 9 years out of date.
4 There is no detail in the link, and....
a) Breast tenderness is subjective.
b) No stats shown on whether the women with breast tenderness who went on to develop cancer had other risk factors- (most in the WHI study had) - overweight, smokers, inactive, over 60.)
The author says this:
Although the present study design did not permit Crandall to directly test whether combined hormone therapy-induced breast tenderness represents increased breast cell proliferation, mammographic density is felt to be an indirect measure of breast tissue growth
It's stating the obvious- that denser breasts sometimes correlate to breast tissue growth.
But breast tissue growth is not necessarily a 'cause' of breast cancer.
And the paper you linked to does NOT prove tender breasts= higher risk of cancer.
What is known is that:
Denser breasts can be associated with breast cancer. This is thought partly to do with mammograms not being able to show small tumours.
It's also well-known ( or should be!) that synthetic progestogens carry a higher risk of breast cancer. The exception is dydrogesterone (in Femoston) and natural progesterone (Utrogestan.)
At your age you are too young for the risks of HRT to apply because you are simply topping up your own levels and will still have a lot of your own hormones circulating.