36 year old with a health question can anyone help?

I just went to the doctor and I guess I have low iron (80 when its suppose to be 120 )what i was wondering is ....could it be my diet?I don`t eat breakfast and almost never eat lunch (if i do its like a banana or grapes ..ect) and for dinner sometimes we don`t even have any meat ..I have to go back today for some other blood test and I`m really worried its colon cancer ...I have no history of it in my family and I 36 how likely its that ?