Delaying cancer treatment by one month can lead to as much as a 13 per cent higher risk of death, research suggests.
UK and Canadian researchers have found there is a significant impact on mortality if treatment is delayed, whether surgical, systemic therapy such as chemotherapy or radiotherapy for seven types of cancer.
The risk keeps rising the longer treatment is delayed, according to the research published in the British Medical Journal.
While it is already widely accepted delays can have adverse consequences, the precise impact of delays from diagnosis to receiving treatment on mortality has not been thoroughly analysed.
A team of researchers reviewed and analysed relevant studies into the subject published between January 2000 and April 2020.
These studies had data on surgical interventions, systemic therapy such as chemotherapy or radiotherapy for seven forms of cancer – bladder, breast, colon, rectum, lung, cervix, and head and neck – which together represent 44 per cent of all incident cancers globally.
Their main outcome measure was the risk to overall survival per four-week delay, and delays were measured from diagnosis to first treatment or from the completion of one treatment to the start of the next.
They found 34 suitable studies for 17 types of conditions needing to be treated involving more than 1.2 million patients.
The association between delay and increased mortality was significant for 13 of these 17 indications.
Analysis of the results showed that, across all three treatment approaches, a delay of four weeks was associated with an increase in risk of death.
For surgery, this was a 6 to 8 per cent increase in risk of death for every four-week delay.
The impact was even more marked for some radiotherapy and systemic indications, with a 9 per cent and 13 per cent increased risk of death for definitive head and neck radiotherapy and follow-up systemic treatment for colorectal cancer, respectively.
In addition, researchers calculated that delays of up to eight weeks and 12 weeks further increased risk of death and used the example of an eight-week delay in breast cancer surgery that would increase the risk by 17 per cent, and a 12-week delay that would cause a 26 per cent increase.
A surgical delay of 12 weeks for all patients with breast cancer for a year would lead to 1400 excess deaths in the UK, 6100 in the United States, 700 in Canada and 500 in Australia assuming surgery was the first treatment in 83 per cent of cases and mortality without delay was 12 per cent.
The authors acknowledged the study’s limitations, such as the fact it was based on data from observational research that cannot perfectly establish cause.
It was also possible patients with longer treatment delays were destined to have inferior outcomes for reasons of having multiple illnesses or treatment morbidity.
But their analysis was based on a large amount of data and they ensured they only included high-quality studies with high validity.
“A four-week delay in treatment is associated with an increase in mortality across all common forms of cancer treatment, with longer delays being increasingly detrimental,” said lead researcher Timothy Hanna.