The Big Dog, real-name Joe Anoaʻi, returned to the WWE ring for the first time in months last night after being diagnosed with leukaemia in October.
Reigns, 33, announced he is in remission and was met with thunderous applause by Raw fans.
The wave of support could propel him into a big name match at WrestleMania in April.
Some Twitter speculated that Reigns’ announcement was a “work” by WWE, noting that he looked the same and that no-one could be beat cancer in such a short period of time.
Leukaemia Care UK has since dismissed the sick rumours in a long thread.
The organisation tweeted: “Relapse is a scary reality for all leukaemia patients. Either fear of your cancer returning or having to face treatment for relapse. It’s great to hear some positive news from a leukaemia patient.
“The tweets we are seeing mainly centre around the idea of what a cancer patient should look like. ‘How can he have hair?’ ‘How can he have not lost weight?’ ‘Why doesn’t he look like a cancer patient?’
“We’re going to weigh in here with some leukaemia information. Back to basics. Leukaemia is a cancer. It affects people of all ages. There are four main types of cancer: ALL, AML, CLL and CML. However, there are other types and subtypes. LEUKAEMIA IS COMPLICATED!
“NONE of us are in a position to question his treatment”
Leukaemia Care UK
“The different types are key. Acute leukaemias are aggressive and need aggressive treatment to save a patient. Chronic leukaemias are incurable but treatable.
“DON’T FORGET – We do not KNOW what type of leukaemia he has. Therefore, NONE of us are in a position to question his treatment, how he should look etc.”
The charity then listed a range of side effects and stated that “there is no one way that leukaemia SHOULD look”.
It is widely expected Reigns will later team up with Ambrose and Strowman to take on the group of Corbin, McIntyre and Lashley.
Vince McMahon has reportedly been taking a more active role in running WWE since the emergence of rival AEW.
He was apparently furious when superstar Hideo Itami decided to leave.