Risk of malignancy ‘markedly’ increased after childhood cancer

Treatment for childhood cancer increases a person’s risk of developing future malignancy.
 
Such were the findings of two new papers on the topic.
 
While this information may be considered common knowledge, the papers highlighted just how significant the problem is, therefore underlining the importance of surveillance and follow-up.
 
One of the new papers was published in JAMA Pediatrics. It concluded that childhood cancer survivors have a much higher risk of developing breast cancer and other malignancies later in life.
 
‘To our knowledge, this is the largest study of treatment-related breast cancer after childhood cancer,’ the researchers wrote.
 
‘We also provide the first evidence that the combination of anthracyclines [chemotherapy] and radiotherapy may markedly increase breast cancer risks and is greater than the sum of their individual effects, consistent with an additive interaction.’
 
That study examined 14,358 childhood cancer patients from the North American Childhood Cancer Survivor Study who were diagnosed between 1970 and 1986 and survived at least five years.
 
Of those, 271 female patients later developed breast cancer at a median age of 39.
 
They discovered that children who received a radiation dose of 10 Gy or more, but no chemotherapy, were nearly 10 times more likely to be diagnosed with breast cancer in adulthood compared to those who received little to no radiation.
 
Children who were also treated with anthracycline therapy were nearly 20 times more likely to develop cancer as an adult.
 
The researchers found the likelihood of a breast cancer diagnosis as an adult increased for every 10 Gy of radiation received and for every 100 mg/m² of anthracycline administered.
 
Meanwhile, a separate new study published in the Journal of Clinical Oncology also examined the same Childhood Cancer Survivor Study cohort.
 
It found the rate of subsequent malignant neoplasms among childhood cancer survivors treated with chemotherapy alone was nearly three times as high as the general population.
 
That study found the increased risk from chemotherapy alone was linked to multiple subsequent cancers, including leukaemia, lymphoma, soft-tissue sarcoma, thyroid cancer and melanoma.
 
The authors noted survivors treated with chemotherapy alone are at increased risk of subsequent malignant neoplasms when compared to the general population.
 
‘Though risk and cumulative incidence were approximately half of what was observed in survivors exposed to radiation plus chemotherapy,’ they wrote.
 
In that study, the 30-year cumulative incidence rate for a subsequent malignant neoplasm was 3.9% for those treated with chemotherapy alone, 9% for those who received chemotherapy plus radiation, and 10.8% with radiation alone, as compared with 3.4% for those who received neither for their childhood cancer.
 
Both studies, based on their respective results, found the need to support surveillance for survivors of childhood cancer.
 
Dr Leanne Super is a paediatric oncologist at Monash Health.
 
She told newsGP the potential long-term effects of childhood cancer treatment on future development of malignancy is well known, and that current treatment of such cancers has been modified to reduce these risks.
 
She said these studies were looking at patients who were treated for childhood cancer around 40–50 years ago.
 
‘Treatment has changed a lot [since then] because of these known side effects,’ she said.
 
‘So we’re using a lot less radiation, and we’re monitoring how much of a particular drug we’re giving.’
 
Dr Super believes adequate surveillance and follow up of such patients is vital and said that, in Australia, this is mainly done through survivorship clinics.
 
When a patient is discharged from such a clinic, Dr Super said they are given a summary or ‘passport’ that details treatments they have received, along with potential side effects and which investigations may need to be followed up by their GP.
 
But not every survivor of childhood cancer is necessarily linked into these services.
 
In those cases, Dr Super said GPs should try to elicit the type of treatment the patient had and should then try to link them to a survivorship clinic so they can attain a ‘passport’ with recommendations of how often they need monitoring.
 
She said such patients may then also require earlier monitoring of standard follow-up, such as breast or skin screening or cardiac monitoring, along with other at-risk organs.
 
For further information on screening post childhood cancer, Dr Super recommends referring to the National Cancer Institute and the Victorian Paediatric Integrated Cancer Service long-term follow-up program.

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