Saturday, 6 December 2014

Risk of cancer associated with autism: small but present

Whilst understanding the power that headlines can have, alongside the way that statistics can sometimes mislead and/or be misrepresented, I don't want to shy away from the findings presented by Huey-Ling Chiang and colleagues [1] reporting that: "patients with autistic disorder have an increased risk of cancer."
Curiosity often leads to trouble.

Based yet again on data derived from the fantastic resource that is the Taiwan National Health Insurance database (see here for some other research examples taken from this dataset), authors looked at the medical insurance records of over 8000 young people diagnosed with an autism spectrum disorder (ASD) living in Taiwan. They found something of an excess risk for various groups and various cancers although only actually recording that: "cancer occurred in 20 individuals with autism". I used the word 'only' in that last sentence to demonstrate how rare a cancer diagnosis was to the autism group as a whole; realising however that for those 20 people, receipt of such a diagnosis probably carried all the emotions for them and their families that one might expect following such news.

The Chiang findings reported in particular an increased cancer risk in relation to males over females and that: "The number of cancers of genitourinary system was significantly in excess of the expected number... and increased risk was found in ovarian cancer." What these findings suggest to me is that awareness and screening for cancer should perhaps be more commonplace in various discussions with autism in mind, particularly in light of how receipt of a diagnosis of ASD seems to offer very little protection against various other comorbidity being potentially diagnosed (see here) and where delays in diagnosis of comorbid conditions can potentially lead. Indeed, other research crossing into some cases of autism concluded something similar [2] when it came to cancer screening access.

Insofar as the other literature on this topic, I do want to go through some additional studies. I am shying away from talking too much about the various research which has for example, implicated some genetic issues with an individual autism diagnosis in mind that have also crossed over into cancer research too [3]. Yes, such studies might be important, but genes and cancer is still a very, very complicated area [4] as indeed, is the current collected literature on genes and autism (see here).

Autism and cancer has previously received a rather mixed review when it comes to any sort of correlation/relationship. The paper from Blatt and colleagues [5] reviewing the records of cases of paediatric cancer for signs of autism concluded that there was not a "high concordance" between the two diagnoses. That being said, their slightly lower participant numbers (N=702) than that included in the Chiang study together with the focus on autism being present in those already diagnosed with various cancers could be seen as study/methodological differences.

A few case reports can also be found in the research literature in this area. The case report from Lisa Radcliff [6] provides an interesting account of breast cancer diagnosis and treatment for a woman diagnosed with autism. Detailing a slightly older age group than the Chiang paper included, the Radcliff paper covered various issues - including legal and ethical - associated with the diagnosis and treatment of cancer also taking into account how autism can manifest and to some extent, complicate things. There are other similar report examples about cancer and autism in the peer-reviewed literature [7] I might add.

The findings reported by Kao and colleagues [8] (open-access) suggesting that "there may be an association between autism and specific forms of cancer" is also worthwhile mentioning in this post. Granted, the authors were looking more generally at 'correlating' autism prevalence and "the Incidence of Specific Female and Male Cancers" for possible shared risk factors, so perhaps again slightly different from the Chiang paper. Their findings however that "the cumulative exposure to estrogen from endogenous and external sources is an established risk factor for both breast... and uterine... cancer, the two cancers that appear to be most consistently correlated with autism" is noteworthy and perhaps ties into some other autism research (see here).

Just before I let this topic go, I do want to pass some comment on the [limited] research asserting that a familial history of certain cancers might show more than a passing relationship to at least some cases of autism. I read something about this quite recently and some, it has to be said, rather disparaging comments about the possibility of any overlap. Without trying to make mountains out of molehills, the paper by Erin Ingudomnukul and colleagues [9] represents one of the primary sources of peer-reviewed evidence suggestive of a possible link between certain types of cancer being present in both women with autism and their first degree relatives. To quote: "Compared to controls, significantly more mothers of ASC [autism spectrum condition] children reported (a) severe acne, (b) breast and uterine cancers, tumors, or growths, and (c) family history of ovarian and uterine cancers, tumors, or growths." This perhaps complements some of the more anecdotal data that I've come across down the years but very much implies that a lot more work needs to be done to confirm or refute such findings.

I want to end this post with a reiteration of the relative rarity of cancer occurring when a diagnosis of autism is received despite the headline of an increased risk present in the Chiang paper. I say this not to downplay the fact that autism is seemingly protective of nothing when it comes to other comorbidity, but merely not to sensationalise this area or add any further worry to those with autism or their families.

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[1] Chiang H-L. et al. Risk of Cancer in Children, Adolescents, and Young Adults with Autistic Disorder. J Pediatrics. 2014. 18 November.

[2] Osborn DP. et al. Access to cancer screening in people with learning disabilities in the UK: cohort study in the health improvement network, a primary care research database. PLoS One. 2012;7(8):e43841.

[3] Crespi B. Autism and cancer risk. Autism Res. 2011 Aug;4(4):302-10.

[4] Dawson MA. & Kouzarides T. Cancer epigenetics: from mechanism to therapy. Cell. 2012 Jul 6;150(1):12-27.

[5] Blatt J. et al. Autism in children and adolescents with cancer. Pediatr Blood Cancer. 2010 Jan;54(1):144-7.

[6] Radcliff L. Breast cancer and autism. J Adv Pract Oncol. 2013 Mar;4(2):113-7.

[7] Kim HS. et al. Squamous cell carcinoma of the lung in an autistic child who has never smoked. J Pediatr Hematol Oncol. 2011 Jul;33(5):e216-9.

[8] Kao HT. et al. The correlation between rates of cancer and autism: an exploratory ecological investigation. PLoS One. 2010 Feb 23;5(2):e9372.

[9] Ingudomnukul E. et al. Elevated rates of testosterone-related disorders in women with autism spectrum conditions. Horm Behav. 2007 May;51(5):597-604.

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ResearchBlogging.org Chiang, H., Liu, C., Hu, Y., Chen, S., Hu, L., Shen, C., Yeh, C., Chen, T., & Gau, S. (2014). Risk of Cancer in Children, Adolescents, and Young Adults with Autistic Disorder The Journal of Pediatrics DOI: 10.1016/j.jpeds.2014.10.029