Can I play Tennis?

Julie, best bet would be to get a referral from any doctor on your team to a well-qualified lymphedema therapist for baseline arm measurements, personalized risk reduction tips, learning a gentle lymph massage that can encourage lymph flow, and fitting for a compression sleeve and glove or gauntlet (fingerless glove) that you can use prophylactically for exercise and travel.

When you start back to any kind of exercise you want to begin veeeeery slowly. If it's tennis you're after, start with just the arm, working up to just the racket (no balls), and go from there, over time. If you experience any achiness, heaviness, or just a "strange" feeling in your arm, stop at once and elevate your arm and rest. You can try again the next day, stopping before that point, and continue to work up more gradually. Stay well hydrated, as it helps move lymph fluid.

There is no "safe" amount of time after treatment -- the lymphedema risk remains for life. An all-clear from your surgeon or onc only means in terms of incision healing or fatigue. It's a rare doctor who knows enough about lymphedema risk to advise patients on that score. Which is why a well-trained lymphedema therapist is the go-to person for the kind of information you're looking for. Here's how to find one near you:
http://www.stepup-speakout.org/Finding_a_Qualified_Lymphedema_Therapist.htm

Fifteen nodes out does increase your statistical odds, but even one node is enough to result in lymphedema in some women (me, for one!) You're really wise to be asking these questions. Wishing you a strong recovery and no "swell" days ever!

Be well,
Binney

Don't give up tennis.  You need to do the things you love.  But do take precautions.  Go to a lymphedema therapist and get fitted for compression garments.  The kind of effort involved in playing tennis coupled with the number of nodes you had removed does put you at heightened risk.  And it is true that your risk won't decline over time.  i developed LE 4.5 years after my surgery.  However, I continue to run and lift weights, I just do so wearing my compression garments.

 My LE therapist's attitude was that we shouldn't give up the things that "make our lives complete."  (I've always loved the phrase she used).  But we do need to be careful so you should seek and rely on a professional opinion.  Good luck and have fun!