Religion had no role to play in recovery or treatment of cancer. Spirituality definitely can help one understand cancer and cure it provided one had the willpower exhibited by Swami Vivekananda.
If one possesses willpower of Swami Vivekananda one could easily kill all cancerous cells in no time. Positive thinking complements spirituality. Remaining positive all the time, invoking positive thoughts all the time we can think logically, indulge in spirituality logically.
Spirituality was all about successfully indulging in contemplation (chintan) most of time. That was how we could dissolve queries within. For a logical thinker possibility of growth of cancer cells did not exist. Even if they do, they would eventually die.
For cancer patients it is best advisable that one indulges in positivity 100% time. No lapses at all!
Remaining positive all the time, thinking logically we can definitely kill all cells that were immobile, inefficient, bad or already dead. From personal experience I can say that total cure of cancer is possible. What mattered is developing a willpower equivalent of Swami Vivekananda.
In practice of spirituality from six years of age when I reached very high levels of spirituality came a stage when I wrote a letter to director-general world health organization to inject me publicly with any lethal disease virus including AIDS. This letter was written about 30 years back and I have yet to receive a reply. This confirms non-belief in practices of Indian spirituality by WHO.
Since that time I have brought down myself too to lower mental levels. I had two young daughters at that time, family responsibilities I had to complete. Could not abandon like Siddhartha Gautama. For above 20 years in a go I was not affected by any kind of viral fever. My body immunity was almost infinite. But now with growing age and family responsibilities still in hand, I do not practice the same as earlier.
I have seen times when I maintained perfect robust health even without indulging in any sort of exercise including aerobics or asanas (yogic exercises). This resulted from my practice of spirituality as detailed in Bhagavad Gita.
As far as religion is concerned, the most we can do is pray to god, worship him. The effect of prayers would be minimal as everything in cosmic system, on mother earth is directly controlled by inscrutable laws of karma, as we sow so shall we reap nothing less or more.
More than prayers, indulgence in positivity, invoking positive thoughts all the time worked wonders.