Hi there Joy is correct you can have a positive ANA w/o getting lupus. My daughters has been positive for years since like age 7 she's 21 now and hers has been 1:640 and she still doesn't have lupus.
It's common to get a positive ANA if you have an infection. Now you're asking about the cancer DX, I've not heard that the ANA shows cancer. I have lupus/RA and LGL leukemia, my cancer was confirmed by my bone marrow biopsy and my other blood work. I know that my oncologist didn't go off of my ANA.
I know that they were looking at my lymphocytes, white count, and other various things. Try not to panic and wait and see what the doctors have to say. If you're not having any symptoms of lupus I'd bet that you don't have it.
I hope everything turns out okay and you have nothing but a positive ANA.
DX- RA, Lupus, Fibro, LGL Leukemia, Obstructive & Central Sleep Apnea, Pulmonary Hypertension, Bells Palsy, Gastroparsis, Blood Clots, Glaucoma, Chronic Pericarditis & Pleurisy, Severe Anemia. Way to many medications to list.