Anni Dewani's killer should have entered into a plea bargain before his trial, a Western Cape High Court judge said on Monday.

"This is a typical case - I don't know if he was badly advised, stubborn or just plain stupid - where he should have entered into a plea bargain given his situation," Judge Robert Henney said in deliberations on the sentencing of Xolile Mngeni.

He had just heard an oncologist testify about Mngeni's brain cancer.

"For 44 days he sat through his protracted trial in his condition... This is going to be one of my most unpleasant tasks, this sentencing," Henney said.

Mngeni was convicted last week of the tourist's premeditated murder.

He was also found guilty of robbery with aggravating circumstances and the illegal possession of a firearm and ammunition.

Dewani was shot dead in Gugulethu on 13 November 2010, in an allegedly faked hijacking. Her body was found the next day.

The court heard on Monday that Mngeni started experiencing severe headaches, vomiting and double vision shortly after the murder.

He suffered for five months until being diagnosed with a pineoblastoma in May last year, while in police custody.

Jeanette Parkes, an oncologist at Groote Schuur hospital, testified that Mngeni suffered from a rare brain cancer, which only one in five people survived in a five-year period.

She said Mngeni underwent surgery shortly after being diagnosed and was receiving radiotherapy and chemotherapy.

As a result of the surgery and treatment, he had poor co-ordination, affecting mostly the right side of his body. He also had poor balance, which explained his need to use a walking aid in court.

A scan last week showed he was clear of the disease.

"It's quite unusual to see such a spectacular response of this type of disease to the treatment," Parkes said.

"In the short term, he's in a good situation, but over the long term, the risk is quite high that the disease will return."

She said a recurrence of the cancer would be most likely be fatal.

Qalisile Dayimani, for Mngeni, appealed to Henney not to impose the minimum prescribed sentence of life, citing the medical condition as a substantial and compelling circumstance.

Henney said he had to balance the medical condition with Mngeni's lack of remorse.

"We now have the situation where the accused person has the strength and energy to go through a protracted trial and shows not a shred of remorse," he said.

He wondered if it was fair to impose a lesser sentence on Mngeni than that meted out to his accomplices, Zola Tongo and Mziwamadoda Qwabe, when they had shown remorse and had both entered into plea agreements.

Tongo was given an 18 year jail term and Qwabe 25 years.