Tim Keller has hailed the "excellent" results of recent scans in his fight against pancreatic cancer. 

The respected pastor and author says he has been moved onto a less aggressive form of chemotherapy after scans revealed a "significant decrease in size and number of tumors".

Keller, 70, has been receiving treatment for pancreatic cancer since last May. It's his second time fighting cancer after previously beating thyroid cancer.

"The Meaning of Marriage" author said he wanted to "honor God and the many who have so faithfully prayed for me" since his treatment began. 

"I was on chemotherapy for 14 rounds, and have had relatively mild side effects, although the neuropathy in my hands and feet increased over time," he wrote on Facebook.

"I'm hoping that will start to improve now that I have been downshifted to a less aggressive (and physically damaging) chemotherapy."

His most recent scan on February 8 showed that one area that previously had "numerous nodules" now has "none visible". 

"I still have cancer, but this is excellent news so we are rejoicing that God has worked through your prayers and chemotherapy to accomplish so much," Keller said.

"What the future holds I do not know, but we will continue to trust His plan and allow Him to shepherd us along his chosen path."