Ultraviolet radiation and carcinogenesis

preparations. : sion of c-fos (which causes genetic aberraporphyrin and thus a tions in the absence of DNA damage) and carcinogenesis potential sensitiser, with implications for the secretion by irradiated cells of factors outdoor workers exposed to plant extracts. : that increase mutations in unirradiated cells. Mutations having the potential to disThere is compelling evidence that ultraThe immunosuppressive effect of UVR violet radiation (UVR) is a complete carrupt function have been found in ras genes in non-melanoma skin cancers and in a contributes to carcinogenesis by making it cinogen, acting at all three of the major for of melanomas. easier tumour cells to escape immunosubset The malignant recognised stages of carcinogenesis-initiof the ras surveillance. UVR causes partial depletion is involved in gene ation, promotion, and progression. This product of the transmission of within conclusion is made in a review,’ produced growth signals antigen-presenting cells in the skin the mutations are to activate the UK National Proteccells; (Langerhans cells) and modification of the thought Radiological by . this to a conof the molecular and cellular tion Board, remaining cells, possibly by preventing process sufficiently provide tinuous growth signal. Mutations of the their expression of intercellular adhesion effects of UVR. According to the International Agency for Research into Cancer, p53 tumour suppressor gene have also molecule-1, so that they inactivate rather been identified in human skin tumours, : than activate certain T-cell subsets. there is enough evidence for solar radia: Another factor contributing to this tion to be considered a carcinogen for especially malignant melanoma. Tumour promotion might be the unman, limited evidence for UVR from sunimmunosuppression is increased secretion intended result of physiological responses of tumour necrosis factor-a. In mice traits lamps and sunbeds, and inadequate evidence for other sources of UVR. The to ultraviolet damage. Such responses for resistance and sensitivity to UVR review concentrates on ultraviolet A include activation of growth signalling immunosuppression seem to be linked to (UVA) and UVB, since solar UVC is pathways, presumably to help in the repair the tumour necrosis factor-a locus. Sugstrongly absorbed by the earth’s atmosprocess. The change in cell signalling is gestive evidence that these traits in man phere and thus presents little risk. : achieved by activation of regulators, which show a relation with skin cancer raises the include proto-oncogenes such as c-fos and possibility of screening for those at risk. Initiating agents act by inducing mutations in specific genes involved in cellular c-jun. The review ends with recommendations : Tumour progression occurs when the for further research. regulation. Underlying such mutations is damage to DNA. In the case of UVA, premalignant cells produced by the first absorption by DNA is enhanced by sensistages of carcinogenesis develop malignant Vivien Choo tisers. Endogenous sensitisers include . phenotypes. Further exposure to LTVR riboflavin, bilirubin, and porphyrins, and contributes to this process by increasing 1 Cridland NA, Saunders RD. Cellular and perhaps steroids, quinones, carotenoids, genetic instability through damage to molecular effects of UVA and UVB. and melanin. Exogenous sensitisers DNA and possibly through cellular London: HM Stationery Office. 1994. include some dyes, drugs (oral or topical), responses such as inappropriate expresPp 95. £10. ISBN 0-85951-374-2. and cosmetic and Chlorophyll is a

Ultraviolet radiation and

’

sunscreen

MEDICINE AND THE LAW

Breast

tionist

litigation, appointed expert witnesses,

implant compensation position,

court-run

court-

and

a

routine maximum of a half day for trials of actions valued at less than 10000. Most of the 250 lawyers present were doubtful that the objectives would be achieved or would benefit private litigants. A central plank of the increased "access to justice" proposals is cost cutting and the funding of claims by introducing contingency fees for solicitors and probably for barristers -and the not-so-hidden agenda of further running down legal aid provision. To deal with the costs implications for unsuccessful litigants, the Law Society has arranged for plaintiffs to obtain reasonably priced insurance cover against the defendant’s costs and for disbursement costs (which will include a medical expert’s, but not barrister’s, fees) in the event that the action is lost, but such cover does not yet include medical negligence claims (presumably because costs of investigation are greater and outcome is much less

The main theme of the autumn conThe UK official medical ference of the Association of Personal v based on a 1992 review, seems unInjury Lawyers was product liability altered and patients have not been in personal injury claims with particformally alerted to the settlement ular focus on the US settlement proposals in the US and the implicascheme available to claimants who tions of the US Food and Drug had silicone gel breast implants Administration’s findings and new . before June 1, 1993, and who must restrictions on these implants. The UK Medical Devices Agency’s stance register before Dec 1, 1994, to qualify for the scheme. Russell Levy of is that there is insufficient evidence to London solicitors Leigh Day & Co deem silicone gel implants unsafe, emphasised that even symptom-free and the agency has not required implant recipients and children of manufacturers to present data suprecipients should register before Dec porting the safety of implants, as occurs in the USA, Australia, and 1, 1994. Claimants who had experienced relevant symptoms could be elsewhere. Dr Scott Kale, a rheumaeligible for considerably larger sums tologist, presented data supporting . from the scheme. The proposed the claim that silicone gel breast agreement between implant manuimplants can and do cause considerfacturers and claimants’ lawyers in able harm (see p 1451 for discussion the US discriminates against foreignof controversy). : ers (see Lancet 1994; 343: 845) and Earlier in the day, in his keynote address on Access to Justice Review, may prove insufficient and so unsatisLord Woolf outlined his proposals for factory that distinct litigation predictable). It remains to be seen prove inevitable. Australians and simplifying the claim process, thus whether lawyers and insurers will Canadians are excluded from the reducing the costs and making "jusfund multiparty actions in this way. scheme. The agreement does not tice" accessible to all who seek it. admit liability. The proposals included the interven- Diana Brahams

may

,

1499