If you believe in the theory of inflammation being a big contributor of cancer,then it would be logical to think:
Touching and love-making releases oxytocin.
Oxytocin is an antioxidant. (see article link below)
Oxytocin reduces inflammation.
Reducing inflammation reduces cancer risk.
Touching and love-making helps reduce cancer risk.
http://molpharm.aspetjournals.org/content/61/2/260.full.pdf
And where do you get the idea that touching releases estrogen?