Famed Christian author Tim Keller has given a positive update on his treatment for pancreatic cancer. Posting on Twitter, Keller credited the power of prayer, noting that his doctor was "surprised and delighted" by his progress.

"Thank you all so much for continuing to pray for me during my treatment for pancreatic cancer," he wrote. "God has been very gracious in answering those prayers, and my most recent CT scans last Monday showed more improvement". 

Keller said that the doctor went as far as to describe the improvement as "incredible.

"We are cautiously trying to be encouraged," he added.

The former pastor of Redeemer Church in New York City, Keller said that he was "able to tolerate the continued high level of chemotherapy with relatively few side effects".

"They are there," he said, "but not as debilitating as they could be as well as having such a strong therapeutic response. Those, of course, are the two things we asked people to pray for!" 

"All praise belongs to God, who has been merciful and generous in caring for us both physically and spiritually," the author declared. "Please, if you are willing, continue to pray."