28-year-old Tomar passed away today, said a doctor at Mumbai's Tata Memorial hospital where she was admitted few days ago, amid indication of relapse of cancer.
Two years ago, she had undergone a surgery for oral cancer at the hospital.
She shared her experience in a video, which was used by the government for its anti-tobacco drive to warn people against consumption of smokeless gutkha and pan masalas.
Just a few days ago, she had written to Prime Minister Narendra Modi expressing deep disappointment at BJP MP Dilip Gandhi's statement in his capacity as chairman of Lok Sabha's Committee of Subordinate Legislations that there was no Indian study to confirm that tobacco use leads to cancer.
"Bigger warnings can probably save some innocent lives like mine. You have started to take people along in your 'Mann Ki Baat' where you recently talked about de-addiction. I hope you will also take up the cause of tobacco," Sunita had written in the letter.