( ( Since ( ( ( excess exposure ) ( to ( ultraviolet radiation ) ) ) ( is ( ( the ( primary cause ) ) ( of ( skin cancer ) ) ) ) ) ) ( , ( ( reducing ( sun exposure ) ) ( ( can ( help ( prevent ( skin cancer ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN Since) (S (NP (NP (JJ excess) (NN exposure)) (PP (TO to) (NP (JJ ultraviolet) (NN radiation)))) (VP (VBZ is) (NP (NP (DT the) (JJ primary) (NN cause)) (PP (IN of) (NP (NN skin) (NN cancer))))))) (, ,) (S (VP (VBG reducing) (NP (NN sun) (NN exposure)))) (VP (MD can) (VP (VB help) (VP (VB prevent) (NP (NN skin) (NN cancer))))) (. .)))
Since excess exposure to ultraviolet radiation is the primary cause of skin cancer, reducing sun exposure can help prevent skin cancer.
(ROOT (S (NP (NP (NNP Exposure)) (PP (TO to) (NP (JJ ultraviolet) (NN radiation)))) (VP (MD can) (VP (VP (VB increase) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NN pigment)))) (PP (IN in) (NP (DT the) (NN skin)))) (CC and) (VP (VB make) (S (NP (PRP it)) (VP (VB appear) (NP (JJR darker))))))) (. .)))