老人与海中一句话不懂,The old man was thin and gaunt with deep wrinkles

老人与海中一句话不懂,
The old man was thin and gaunt with deep wrinkles in the back of his neck.The
brown blotches of the benevolent skin cancer the sun brings from its [9] reflection on the
tropic sea were on his cheeks.The blotches ran well down the sides of his face and his
hands had the deep-creased scars from handling heavy fish on the cords.But none of
these scars were fresh.They were as old as erosions in a fishless desert.
其中的：The
brown blotches of the benevolent skin cancer the sun brings from its [9] reflection on the
tropic sea were on his cheeks.
一句话是啥意思?为啥还有cancer?