English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Wu et al.(1) have based their studies on the assay of Hsu et al. (2) who developed the bleomycin sensitivity assay in which the number of chromatid breaks induced byin vitro exposure to bleomycin in short-term cultures of peripheral blood lymphocytes was assessed to estimate host susceptibility to neoplastic cell transformation. Wu et al. (1) investigated the susceptibility to bleomycin and benzo[ a]pyrene diol epoxide of chromosomes of lymphocytes from subjects who were previously treated with surgery, radiotherapy, or both for stage I or II squamous cell carcinoma of the head and neck and from healthy subjects. They concluded that the people who were sensitive to both mutagens were at 19.2-fold increased risk of cancer of the upper aerodigestive tract. In my opinion, Hsu’s hypothesis is not applicable in all cases. Indeed, both the ataxia-telangiectasia (AT) heterozygotes and the homozygotes are cancer prone. Only about 10%–20% of homozygotes develop neoplasms, mostly lymphomas and leukemias. Retrospective studies have indicated a substantial increase in all cancers for AT heterozygotes. But chromosomes of homozygote individuals are very sensitive to mutagens, whereas those of the heterozygotes are not(3). Recent investigations have shown that bleomycin was much less effective in inducing DNA damage in leukocytes from children with thyroid cancer than those from healthy subjects (4). Therefore, the sensitivity of lymphocytes of subjects to bleomycin is not a good predictor of high risk of cancer in all cases. The authors have used the term “clastogenic” to include both mutagenic and carcinogenic effects. But the term clastogenic means chromosome damaging. Wu et al.(1) have noted that the frequencies of spontaneous chromatid breaks are extremely low in normal subjects and in case patients. But Hastak et al. (5) have shown that patients with precancerous oral lesions, e.g., oral submucous fibrosis, oral leukoplakia, and oral lichen planus, showed an increase in the

Re: Benzo[a]pyrene Diol Epoxide and Bleomycin Sensitivity and Susceptibility to Cancer of Upper Aerodigestive Tract