Is the Ookisa Hair Care System Safe to Use?

I had Breast cancer in 2006 and in remission. Eversince taking Tamoxifen (to control the estrogen level), I notice my hair take very long to grow. For 3 years, my hair only grow to the base of my neck, whereas before cancer it only took 6 months for my hair to reach the back.

I often see the commercial pop-up for Ookisa. It supposes to strengthen and stimulate hair follicles to grow more hair.

My hair is very fine and I would like very much my hair to increase in number rather than length. Is Ookisa safe for me to use ? I don't want to have another cancer.