Cancer

To the Editor: We read with interest Mendelson and colleagues’ article regarding the underutilisation of computed tomography colonography (CTC) for colorectal cancer detection in Australia.1 The authors state that “CTC is less accurate in the diagnosis of small or diminutive polyps … However, in the context of symptomatic patients, this is not relevant”.1 This overlooks the importance of detecting small adenomas as well as flat, right-sided colonic lesions such as sessile serrated polyps. It is well established that the early detection and treatment of these lesions reduces interval colorectal cancer.2 To state that these are “not relevant” in symptomatic patients is inaccurate. High definition white light with the aid of chromoendoscopy tools such as narrow band imaging in optical colonoscopy (OC) has significantly improved the ability of endoscopists to detect diminutive and subtle lesions. CTC has a markedly limited ability to detect small and flat lesions when compared with OC.3 The authors reference phase 2 data from the National Bowel Cancer Screening Program, stating that “the great majority of OCs (about nine in ten) were normal”. However, polyps were detected in 34.9% of participants.4 The authors appear to define normality as the absence of a cancer or advanced adenoma (one in ten colonoscopies). We argue that the detection of any adenoma is important and is not “normal”, as it highlights a cohort of patients at risk of colorectal cancer and requiring ongoing polyp surveillance. We also question the authors’ suggestion that a negative CTC obviates the need for OC in lower risk patients with positive faecal immunochemical test results. OC provides the opportunity to detect and treat a range of polypoid and non-polypoid colonic pathology and although a negative CTC may help exclude a cancer, it does not address the range of other potentially morbid or precancerous causes of occult faecal blood. Given these limitations, a cautious approach should be adopted if CTC is to be used as an alternative to OC in all lower risk patients.

Simon Hew · Zaid SM Ardalan

In reply

Richard M Mendelson · Tom R Sutherland · Andrew F Little

To the Editor:High technology solutions to the difficult task of selecting and monitoring moles (pigmented skin naevi) may be useful to keep accurate records of people’s skin. Adopting military surveillance and warfare technology,1 there are computer algorithms that search for changes in moles’ appearance over time. Deep convolutional neural networks analysis can group them into benign or malignant lesions with high accuracy.2 In a study by Esteva and colleagues,2 the convolutional neural networks algorithm differentiated between benign, malignant or non-neoplastic lesions with about 72% accuracy compared with about 66% accuracy by two dermatologists; for melanocytic lesions, the algorithm had a better sensitivity and specificity performance compared with the average of 21 dermatologists, although these findings still need to be replicated in independent datasets. Despite recent advances, there are still questions about how Australians can benefit from this technology and how it is best integrated into clinical practice. Cancer agencies worldwide do not recommend screening for melanoma, but instead ask people to make skin self-examinations a habit and present to a doctor with moles of concern — although informal screening is widespread in Australia. Apps that provide easy access to personalised risk estimation may alert people to engage in such exams more frequently. Moreover, apps that guide people through the skin self-examination process may also be useful, as most people find this task complex.3 Once people notice a spot or mole, they may seek a clinical skin examination. Evidence that clinical skin exams are beneficial comes from the Queensland melanoma case control study4 and other similar studies that show that they lead to the detection of thinner melanomas. There are many apps that allow people to take and send photos of moles, but these are highly variable in sophistication and costs. Whether such technology is best placed in front of (for filtering out clearly benign lesions) or after a clinician’s diagnosis (for additional validation) is also matter of debate. Apps should not distract from the patient–doctor relationship, as the final decision about excision requires face-to-face consultations. While technology solutions are promising, validation studies have mostly been small, have lacked a control group or have not been replicated in clinical practice. Independent big research initiatives, such as the International Skin Imaging Collaboration Challenge on Skin Lesion Analysis towards Melanoma Detection,5 are underway to take the momentum further. This healthy competition may be just what is needed to take the last steps to eradicate melanoma.

Monika Janda · H Peter Soyer

To the Editor:The well researched narrative review by Bourke and colleagues1 offers a comprehensive overview of immune-related adverse events (irAEs) in cancer immunotherapy and their management. However, care needs to be taken in adopting too broad an approach, particularly in relation to dermatological irAEs. In the article, “rash” is described as an irAE. However, a rash is a clinical sign, not a diagnosis. The cutaneous irAEs reported in association with immune checkpoint inhibitor therapy span a spectrum of dermatoses including (but not limited to) vitiligo, eczema, lichenoid reactions, morbilliform eruptions, prurigo nodularis, bullous pemphigoid, papulopustular eruptions, rosacea, and cutaneous fungal, bacterial and viral infections.2,3 Categorising every cutaneous irAE as a rash precludes patients from obtaining an accurate diagnosis, which in turn encumbers treatment. Topical corticosteroids are a reasonable first-line treatment option for most pathologies (unless the cutaneous irAE is an infection or papulopustular eruption). However, there is a range of corticosteroid molecules, potencies and vehicles, as well as off-formulary preparations available,4 and physicians should be familiar with this class of drugs before prescribing them. Where accurate diagnosis of a cutaneous irAE becomes particularly important is when topical corticosteroids fail. Systemic corticosteroids, while helpful in containing an acute disease process, are seldom the second-line treatment employed by dermatologists. Dermatologists have an arsenal of topical, physical and systemic therapies at their disposal, and the choice of second-line treatment is determined according to diagnosis. We would therefore offer that a multidisciplinary approach is important in the management of the cutaneous toxicities of the new generation of oncological treatments; not only the moderate and severe as suggested, but also the mild and life-threatening. We commend the rapid rate at which our colleagues in medical oncology have become versed in the fundamentals of dermatological care and recognise only too well the limitations in access to dermatology, even in many of the larger teaching hospitals across Australia.5 However, in many respects, this new era of immunotherapy is uncharted territory, and managing the cutaneous toxicities of these medications necessitates an appreciation of the nuances of managing skin disease.

Rose Liu · Pablo Fernandez-Peñas · Deshan F Sebaratnam