A surprisingly high number of incident cancer cases involve people who have already survived a previous cancer, US researchers have found.
Their study, published in JAMA Oncology, looked at around 750,000 people diagnosed with a new cancer from 2009 to 2013. It found that a quarter of patients over the age of 65 had already survived at least once cancer, while 11% of younger patients had a prior cancer history.
Prevalence of a prior cancer ranged from 3.5% to 37%, depending on the type of incident cancer diagnosed and the age of the patient.
In younger patients, prior cancer was most prevalent in those diagnosed with leukaemia (25%), bowel cancer (18%), cancers of the female reproductive organs (15%) and lung cancer (14.6%).
In those over the age of 65, more than a third of melanoma patients had a prior history of cancer. This was also the case for patients with incident leukaemia and cancers of the bone and joints. Most prior cancer among the older age group occurred in a different site.
Over 30% of older people diagnosed with cancers attributable to human papilloma virus or tobacco use had a prior cancer.
The high rate of prior cancer in leukaemia patients might reflect the leukaemogenic effects of earlier cancer treatments, the study authors from the University of Texas said.
They noted that prior cancer has important implications for cancer care delivery.
“Patients may have competing priorities concerning treatment decisions: a new diagnosis may interrupt management, treatment adherence, or outcomes related to a prior cancer. Differences in the prevalence of prior cancer by incidence cancer type also highlight underlying or shared risk factors that may be amenable to targeted surveillance,” they wrote.
In a linked editorial, clinical oncologist Dr Nancy Davidson argued that the findings “should spur us to revisit our long-accepted policies of excluding many otherwise well patients with a history of previous early-stage invasive cancer from participation in cancer treatment trials”.
She said these common restrictions greatly limit the participation of older patients, the very population where cancer is most commonly diagnosed and where we are most in need of strong evidence to guide treatment.
“As the population of cancer survivors continues to grow, understanding the nature and impact of a prior cancer is critical to improving clinical trial accrual, generalisability of results from trials and observational studies, disease outcomes and patient experience,” the study authors concluded.
Rare cancers are just that: rare. This means research into each of these particular types of rare cancers is limited, and so are the treatment options. As a consequence, patients diagnosed with rare cancers face significant challenges.
The minister also commissioned new work on evaluating cancer medicines that treat multiple tumours and have a specific genetic feature (biological marker). This could improve access to therapies that might benefit some patients with rare cancers.
These recent steps are in recognition of the significant challenges associated with undertaking research into rare cancers. By their nature, rare cancers include small and variable patient populations making gold-standard randomised trials challenging or even impossible.
The lack of evidence resulting from few or no randomised trials creates challenges for registering and reimbursing new medicines. This ultimately leads to a lack of subsidised medicines for these patients. As a result, the improvements seen in patient outcomes related to new therapies for more common cancers like lung cancer, melanoma and bowel cancer over the last two decades do not extend to rare or less common cancers.
What is a rare cancer?
The definition of a rare cancer is debatable. The RARECARE collaboration in Europe uses an operational definition of fewer than six cases per year per 100,000 population. In Australia, the medicines regulator, the Therapeutic Goods Administration (TGA), has recently updated the eligibility criteria for medicines treating rare diseases to fewer than five cases of the disease in a population of 10,000 people.
Historically cancers were categorised by the anatomical location, such as the breast or kidney. But with the discovery of new biological markers, common cancers can be grouped into smaller, more homogeneous and genetically similar subsets. So the number of rare cancers will continue to grow as medical technology advances.
Why don’t they have many available medications?
The lack of government-approved and subsidised medicines to treat rare cancers primarily stems from the lack of evidence supporting their use. Submissions to the current inquiry also cited problems such as a lack of research funding; the need for international collaboration; lack of investment by industry; attracting sufficient interest of researchers and recruiting sufficient patients.
Even if patients can be identified and recruited to a trial, it’s difficult to generate meaningful data from so few patients.
The lack of evidence presents challenges for new medicines trying to meet registration and reimbursement criteria in Australia. To be registered through the TGA, a new medicine must have demonstrated efficacy and safety.
In order for new medicines to be listed on the Pharmaceutical Benefits Scheme (PBS), it must have a demonstrated benefit over standard treatment, as well as being considered an efficient use of tax payer dollars.
New medicines for rare cancers are often expensive, especially when randomised trials are not possible.
What can we do to improve this situation?
With the changing nature of medicine and research, new opportunities are emerging to address the current inequity. The shift to treating patients based on the genetic profile of their tumour rather than the location of the cancer has increased treatment options for rare cancer patients.
To harness the benefits, changes are required with input from multiple stakeholders, including government, industry, clinicians, researchers and patients.
Better access to new medicines ultimately starts with better research. To achieve this, experts have called for additional targeted funding, innovative trial designs, and better partnerships between industry and researchers.
There is also the opportunity to collect better “real world” data via platforms such as the My Health Record, which could supplement existing research and allow performance monitoring of recently approved new medicines.
Organisations such as Rare Cancers Australia and the Cancer Drugs Alliance are liaising with government regarding changes that could improve access to novel medicines for patients with rare cancers. This includes greater input from patients and more flexibility in the way we evaluate medicines for public reimbursement.
It should also be recognised the problems faced in providing innovative treatments to patients with rare cancer extends to rare diseases in general. With modern medicine providing the potential to improve outcomes for patients with rare cancers as well as other serious chronic diseases, we need to have a broader conversation about what we can afford and what we are willing to pay for new medicines.