Just 11.9 per cent of women with an urgent referral to a breast cancer specialist were seen within 14 days in the Northern Trust in September.
According to the latest figures published by the Department of Health, 19.2 per cent managed to get an appointment in August and 59.2 per cent in July.
The Northern Ireland average was 92.1 per cent, in July, 79.5 per cent in August and 74.5 per cent in September.
The figures for the Northern Trust were also below average for cancer patients starting treatment within 31 days - 90.2 per cent in July, 81.4 per cent in August and 82.8 per cent in the region in September.
A spokesperson for the Northern Trust said: “Over the summer months, the Trust experienced a high level of demand for breast assessment that was far in excess of the Trust’s capacity to see all patients within 14 days of referral. This resulted in an increased number of patients waiting greater than 14 days to be seen in the breast clinic.
“The Trust took action to address this position by securing additional in-house breast assessment clinics in Antrim and also in a neighbouring Trust. The Northern Trust breast consultants also undertook additional theatre sessions to support.
“From the beginning of November 2018, the Trust has been back to seeing 100 per cent of breast red flag patients within 14 days of receiving the referral.
“As the Trust has a gap between demand and capacity in the breast service, it impacts also on the 31 day cancer standard. Additional theatre sessions were provided to operate on patients with confirmed breast cancer which resulted in an improvement in this standard in October and November”.
Ulster Unionist health spokesperson Roy Beggs MLA said that he has written to the chief executive of the Northern Trust to express his concern over the alarming “drop off” during the summer.
He commented: “Cancer is a cruel disease that thrives during any avoidable delay in treatment. That is why it is so important that patients are seen, diagnosed and receive treatment on time.
“Yet once again there has been a further fall in the number of local patients who are receiving treatment on time. Last November, I highlighted the crisis in breast cancer services in the Northern Trust, and now we have confirmation that for the last recorded period only 61.8 per cent of patients in Northern Ireland commenced their first treatment within 62 day following an urgent referral for suspect cancer.
“This is a further decline from the position 12 months ago. It’s outrageous and totally unfair to force so many people to wait for so long.
“In the Northern Trust, the percentage of cancer patients commencing first treatment within 62 days has dropped from 69.4 per cent in September 2017 to 55.8 per cent in September 2018.”
Roisin Foster, chief executive of Cancer Focus Northern Ireland, said: “The continuing failure to meet targets set for patients waiting for diagnosis and cancer treatment is of major concern.
“This places enormous stress on patients and on their families – waiting and worrying. They are fearful that their condition will worsening and will require more complex treatment.
“We know that early diagnosis and treatment saves lives and for many cancer patients time is not a luxury they can afford. We need our politicians back in Stormont to improve waiting times for cancer patients. The sooner we have our new cancer strategy in place the better.”