What would you have done?

I knew a girl, who was my school mate. She died of cancer. No one knew she had cancer. When she was in school, we use to see her tie her head with a . I asked her friend, why she does that, they just said because she took some wrong medicine and the side effect she lost her hair. I believed what they said, but deep inside, who would believe such a thing..
After we've left school, i use to wish her for new year and she would reply. Until one year, for some reason, i did not wish her. The following year, i bumped into her friend. That is when i got the news that she passed away a year ago... due to cancer. At that moment, thoughts pass through me, what would i have done, if i knew she was having cancer, would i have treated her differently.. or would i have been this way... What would you have done?