The 28-year-old received the diagnosis after he joined Borussia Dortmund for £31million in July.
Advertisement
Haller, on the back of a stellar campaign for Ajax which saw him score 34 goals across all competitions, was feeling unwell whilst on pre-season with Dortmund.
He underwent tests which revealed a malignant tumour, with the news bringing huge shock to the football world.
Advertisement
Haller has since undergone chemotherapy, and has returned to the training pitch to continue his recovery.
Ajax manager Alfred Schreuder has since confirmed Haller is training with his side ahead of their match against Liverpool on Wednesday.
"He asked us if he could come and train because he was rehabilitating here," Schreuder said.
"Then it is of course wonderful that he can be there for a while. He was able to train on a different pitch to help his recovery."
Advertisement
Advertisement
Haller previously gave an insight into the treatment he is receiving after conducting an interview with UEFA.
The striker revealed he spent 'five days at a time at the hospital, where I am hooked up 24/7' and cannot get out of bed while the treatment is injected. He then has a two-week rest period.
"That's one phase, and I have to do that four times. Four phases of chemotherapy lasting roughly three weeks each," he added.
Advertisement
"After that, depending on how my cancer is progressing and how it is spreading, I may be forced to undergo surgery.
"A lot of people are asking me when I will be back, but there's a lot to take into account so it's hard to give them a straight answer."
Haller was expected to be out for sometime, but now has a 'timescale in mind' around returning.
Advertisement
"I'm lucky enough to feel well," he said.
"I am physically able to work, I feel fine from both a mental and a physical point of view, which is of course helpful to fight this disease. I have a timescale in mind.
"If I'm lucky enough not to need surgery, things can go very quickly. Three weeks after the final phase, checks are made to see what stage the metastasis is at, and whether you require surgery or not.
"If I don't need an operation, with the way I train, I'd like to think that I will be in good condition at the end of those three weeks."
Advertisement