Sugar and cancer

My oncologist told me to not eat sugar or carbs that convert to sugar while I had the cancer tumor. Now that it is gone and on tamoxifen medication what is a good diet?
I like Mediterranean food so that is where I tend to lean. I eat lots of veggies for dinner and in my breakfast omelet.

I’m no professional dietitian, just someone who does a lot of personal research on diet health.
Everything I’ve read essentially says that sugars feed cancers. Prior to my diagnosis and surgery I avoided sugar, ate one healthy meal a day, 5 days a week, and did occasionally 48 hour fasts. That combined with walking 45 minutes a day, seemed to keep my weight optimal. I was also healthy, but found a breast lump.
Since my surgery I have been healing exceptionally well, per my doctor’s statements. But I have had less healthy, comfort foods, which include things with sugar. I don’t have much support, and have turned to food.
Overall I’d say avoiding sugar is a very good thing, but I’m not sure that it is a make or break thing in preventing cancer. Certainly not in my case. What I choose to do (in a healthier state of mind) is to eat foods that are not processed or minimally processed. As close to their original form as possible. And get outdoors, in nature and sunlight. I don’t know if that’s why I’m healing well, but I believe it helps.

I've read on other cancer forums that once a diagnosis was given, sugar should be avoided. Some drs will tell their patients this but not all of them do. Many drs will just say follow a healthy diet.