Uganda's only radiotherapy machine used for treating cancer is broken beyond repair, the country's main cancer unit says.
This leaves thousands unable to get potentially life-saving treatment.
The cancer unit at Mulago Hospital in the capital, Kampala, is now looking for $1.8m (£1.3m) to buy a new machine.
It gets 44,000 new referrals a year from Uganda, as well as from neighbouring countries including Rwanda, Burundi and South Sudan.
Around 75% of these may require radiotherapy, the unit's spokesperson Christine Namulindwa told the BBC on the phone from Kampala.
"It's really, really a hard time," she added, "[and] it's having an impact on our patients, as the treatment is often required."
Radiotherapy uses radiation to target and kill cancerous cells in a specific part of the body, and can be used for many types of cancer.
Healthy cells can recover from this damage, while cancer cells cannot.
The machine at Mulago Hospital was second hand when it was donated in 1995 and has been repaired several times in the past.
But efforts to fix it this time have failed, Ms Namulindwa said.
The cancer unit is currently talking to the ministry of health to find a way to buy a new machine, but it is not clear when that will happen.
'Travel to Kenya'
The ministry's director of cancer treatment, Dr Jackson Oryem, told BBC Focus on Africa radio that a new machine should be delivered within the next year.
He said that funding was not the problem, rather that there were some technical difficulties - such as the need to build new special facilities - that were causing a delay.
In the meantime, patients are still able to get other treatments, such as chemotherapy and surgery, but if they need radiotherapy, and they can afford it, they will have to travel to neighbouring Kenya.
Dr Oryem said the government may be able to fund a trip abroad for some of the most urgent treatable cases.
The incidence of cancer is on the rise in Africa overall as life expectancy increases.