The 32-year-old told fans last October that he was battling grade IV glioblastoma - an inoperable brain tumour, which has a life expectancy of anywhere from three months to 18 months on average, after diagnosis.
However, in a more positive message to his fans on Thursday, Tom said: "SIGNIFICANT REDUCTION. These are the words I received today and I can't stop saying them over and over again".
He went on: "I had an MRI scan on Tuesday and my results today were a significant reduction to the tumour and I am responding well to treatment. Everyday I'm keeping on the fight to shrink this b*st*rd!
"I can't thank our wonderful NHS enough. You're all having a tough time out there but we appreciate the work you are all doing on the front line."
Taking a moment to honour his wife, Kelsey Hardwick, he added: "To my amazing wife @being_kelsey who has literally been my rock.
"My babies- I fight for you every second of every day.
"Friends, family and everyone on this journey with me- you have got me through my darkest days.
"To everyone on here- your love, light and positivity have inspired me. Every message has not been unnoticed they have given me so much strength.
"This journey is a rollercoaster that's for sure. Today is a f*cking good day".
Tom made the announcement alongside a beaming picture alongside Kelsey, one year old Aurelia-Rose, and their new arrival, son Bodhi.
While the prognosis for those with Tom's tumour is often a matter of months, figures suggest that patients have a 10 percent chance of living five years after their diagnosis.
The singer is now undergoing radiotherapy and chemotherapy so he can support his wife, daughter and newborn son for as long as possible, and to "raise awareness of this terrible disease".
When announcing Bodhi's birth in November, Tom said to OK! Magazine: "Bodhi means enlightenment. So it just goes perfectly with our situation right now. He's the light at the end of our tunnel."
We're so happy Tom has received some positive news.