Don't pink wash it by buying some product.
Don't seek attention for yourself by asking for people to notice that you know someone touched by cancer (hint - we all do, it's not that uncommon).
Don't be condescending and victim blaming by using words like "battle" and "brave". Most cancer patients have many, many days when they don't feel like battling and being brave, and that's OK.
You want to make a difference?
Fork over some bucks to primary research.
Write a letter to your senators and representatives letting them know that you support, and expect them to support, and FUND, fundamental cancer research.
Make a meal for a family currently dealing with this, but ask first if/when it's convenient, and if there are any foods you should avoid - and then actually show up when you said you would.
Ask what they want and need, then listen and follow through - clean a patients house, do some laundry, pull some weeds.
And most of all, remember that people with cancer are just that - PEOPLE who happen to have an illness that every single one of us will have, if we live long enough.