Cancer charities have urged the NHS to ensure sufferers are not affected by cyber attacks in future.
Some 139 people with referrals over possible diagnosis of the disease saw appointments cancelled by May's global WannaCry attack which crippled health service computers.
They were among almost 19,500 appointments lost to the ransomeware, which demanded money to unlock files.
Moira Fraser, director of policy at Macmillan Cancer Support, said patients "should not be subjected to avoidable delays due to IT".
She added: "Being told you have cancer can be one of the most stressful experiences of a person's life, and waiting to start treatment can be fraught with anxiety.
"If an urgent referral is cancelled, whatever the reason, this can delay someone starting treatment.
"A secure, efficient IT infrastructure is clearly a vital aspect of timely cancer care.
"The NHS must take steps to ensure that people's cancer treatment is not affected by future cyber attacks.
Sara Bainbridge, policy manager at Cancer Research UK, said it was "concerning" that people had to wait longer for tests because of the attack.
She said: "The report doesn't show us what happened to the referrals after they were cancelled, so it's difficult to know what effect this had.
"Hopefully the appointments were rescheduled promptly and it's reassuring that no patient harm was reported.
"Every effort should be made so that this can't happen again."
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