If a woman has unequal breast sizes, does the larger breast have a higher chance of getting breast cancer (just because it's bigger)?

No.. There is no correlation between the risk of breast cancer and the size of one's breast.
Uneven BreastS. The answer to my knowledge is no. Size of breast has nothing to do the chances of getting cancer in the breast.
No. Many women will have asymmetric breasts- one would be smaller or bigger than the other. It is normal, by the way. Just because the size is bigger does not mean the risk is higher. Size does not have anything to do with the risk for developing breast cancer.