Cancer can be cured and in most cases can be cured if diagnosed in stage 1 or 2. In stage 3 also with latest treatment modalities can be cured but still, there is a chance of relapse.
In stage 4 Cancer can't be cured in most cases but we can prolong life and give a better Quality of life by decreasing symptom burden. But there is a Rainbow on the horizon in stage 4 Cancer cases with a very small percentage of cases that can be completely cured with Immunotherapy Drugs specially in Melanoma, Rectal Cancer, and other cancers with MSI positive.
Today these Curable stage 4 Cancers can be a very small percentage but I am sure within a decade the cure percentage will increase in stage 4 Cancers at a greater pace.
20 years before there was no hope for stage 4 Cancers, 15 years back Targeted Drugs came which led to the Era of Precision with dramatic improvement in Quantity and Quality of Life with Oral tablets.
7-8 years before Immunotherapy Drugs came with sometimes miraculous results in a patient on a dead bed. Similarly, CAR T cells are there with a cure as adoption in Hematological malignancies where we have exhausted all hopes.
But still, a few stage 1 and 2 cancers come back after being cured for many years or months so the Cancer genomics mystery still is ahead of today's science. But we are hopeful that Cancer will be a curable disease like any infectious disease.
