Myeloma UK’s A Life Worth Living report found half of patients were diagnosed late.
And 49% of patients living with incurable blood cancer suffered a high impact on their quality of life due to missed diagnosis, while 34% suffered debilitating spinal fractures.
The charity is now calling on the Scottish government to make quality of life a key part of the next cancer strategy.
Shelagh McKinlay, the charity’s acting director of research and patient advice, said the delays had caused ‘irreversible’ damage.
About 457 people in Scotland are diagnosed with myeloma each year, which arises in the bone marrow, and late diagnosis is more likely in younger patients.
Although it is one of the most difficult cancers to diagnose, there is currently no target or timeframe for myeloma to be detected early or in a reasonable time, according to the charity.
Ms McKinlay said: “The quality of life for people with myeloma has never been more important, with advances in treatment allowing patients to live longer than ever.
“Delay in diagnosis is well known to increase the likelihood of patients experiencing two or more serious complications.
“Yet there are still no specific diagnostic targets to ensure that the disease is detected and treated in time and to combat unacceptable and truly harmful delays.
“It’s doubly unfair since we know that myeloma outcomes are already so poor.
“From severe and chronic pain, to spinal fractures, kidney damage and other complications, myeloma patients are doomed to a lifetime of limitations because they were diagnosed far too late.
“From the start, their potential to live well is severely limited, regardless of the treatments they receive – the damage is irreversible.
“With a cancer control strategy on the horizon, now is the time to put quality of life at the heart of government policy.
“The Scottish Government urgently needs to develop targets that improve the patient experience and put the daily lives of people with myeloma at the center of research, policy-making, up-scaling and practice. clinical.
“We cannot and will not allow people’s lives to be diminished by avoidable delays in diagnosis.”
It is likely that the diagnostic delay has been exacerbated by the Covid-19 pandemic, which could lead to an increase in the number of patients suffering from one or more serious complications.
A Scottish Government spokesperson said: “The NHS remains under sustained pressure as a result of Covid-19, with the number of people awaiting diagnostic tests at the highest level since 2018, and we are working tirelessly with the health advice to provide vital services.
“We continue to see an increasing number of referrals for cancer and our priority is to ensure that these people receive cancer diagnosis and treatment safely, and according to their clinical urgency.
“Ten million pounds of additional funding has been allocated to improving cancer waiting times in NHS Scotland in 2021/22, with a further £10 million for 2022/23.”