Black and Asian people in England have to wait longer for a cancer diagnosis than white people, with some forced to wait an extra six weeks, according to a “disturbing” analysis of NHS waiting times.

A damning review of the world’s largest primary care database by the University of Exeter and the Guardian discovered minority ethnic patients wait longer than white patients in six of seven cancers studied. Race and health leaders have called the results “deeply concerning” and “absolutely unacceptable”.

The analysis of 126,000 cancer cases over a decade found the median time between a white person first presenting symptoms to a GP and getting diagnosed is 55 days. For Asian people, it is 60 days (9% longer). For black people, it is 61 days (11% longer).

Diagnosis delays may mean fewer treatment options while starting treatment later may also mean it is less effective – reducing the odds of survival. Previous research had already shown that ethnic minority patients have worse outcomes when it comes to some cancers in England and are less likely to report positive healthcare experiences.

Some of the differences in wait times for specific cancers are incredibly stark. The median time for white people to get a diagnosis for oesophagogastric cancer – of the stomach or oesophagus – is 53 days. For Asian people it is 100 days, more than six weeks longer than the median seven weeks’ wait for white people.

In myeloma, the third most common type of blood cancer, the median diagnosis wait time for white people is 93 days. For black people, it is 127 days – more than a month longer.

The government and the NHS have repeatedly promised to tackle ethnic inequalities in healthcare. Experts say the findings show serious action is needed to understand how and why black and Asian people wait longer – and to prevent it from happening.

“These findings are deeply worrying, with potential life-altering consequences for the health of black and Asian people,” said Jabeer Butt, the chief executive of the Race Equality Foundation.

The differences are “disturbing” but “sadly not surprising”, he added. “We urgently need to address these underlying factors holding black and Asian patients back from getting a fair chance when it comes to fighting cancer.”

The University of Exeter looked at 126,000 cancer cases in England between 2006 and 2016. The data covered the four most common cancers – lung, breast, prostate and colorectal – and three commonly diagnosed in ethnic minorities: oesophagogastric, myeloma and ovarian.

The findings “help explain” why ethnic minorities “have poorer outcomes for some cancers, and report worse experiences of healthcare”, said the University of Exeter researcher, Tanimola Martins. “We urgently need to understand why this is the case for black and Asian groups.”

Michelle Mitchell, the chief executive of Cancer Research UK, which funded the research, said that while the differences are “unlikely to be the sole explanation for the inequalities in cancer survival”, at the very least “extended wait times may cause additional stress and anxiety for ethnic minority patients”.

A review of the data by the Guardian found that in six of the seven cancers analysed, black or Asian patients waited longer for a diagnosis than white patients. The exception was lung cancer, where the median wait time was 103 days for black patients, 115 for Asian patients, and 129 for white patients.

The median myeloma diagnosis wait time for black people was 37% longer than for white people, the Guardian also discovered. Dr Sophie Castell, the chief executive of Myeloma UK, said myeloma patients in general, and black patients in particular, experience some of the longest waits for a diagnosis in the country. The disparity will probably worsen as a result of the pandemic, she added.

“The longer it takes to be diagnosed, the more likely patients are to suffer avoidable yet irreversible, lifelong complications like broken bones and spines,” she added. “This is absolutely unacceptable. Everyone deserves the same opportunity to get a timely diagnosis and live well for as long as possible.”

With breast cancer, the difference in diagnosis wait times becomes even larger among the patients waiting the longest. Overall, the median wait time was 13 days for white patients, 13 for Asian patients, and 14 for black patients. The gap between black and white patients grows alarmingly among the 10% of patients waiting the longest.

The median for white patients waiting longest is 41 days, for Asian patients it is 56, and for black patients it is 73. It means black patients waiting the longest for a breast cancer diagnosis wait an entire month longer than white women also forced to wait.

Delyth Morgan, the chief executive of Breast Cancer Now, said black women were more likely to be diagnosed with more advanced breast cancer, for which survival outcomes are poorer.

She said: “It’s deeply concerning that this data suggests black and Asian women may also be waiting longer than white women to receive a diagnosis of breast cancer after presenting with symptoms and we urgently need to understand why this is the case.”

The revelations follow a series of stories by the Guardian exposing major health disparities in England and the UK. Mitchell said that more “needs to be done now” to “understand and tackle drivers of inequality.”

“For this to happen, our next prime minister needs to make cancer a priority. Crucially, they must take targeted action to address inequalities and ensure a important timely diagnosis for everyone.”