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One Pap smear of benefit in developing countries
Newsdesk
Small subsets of cells initiate brain tumours Researchers have found that a small number of brain-tumour cells have the ability to initiate new tumours or to maintain tumour growth (Nature 2004; 432: 396–401). “These key cells—tumour-initiating cells or cancer stem cells—self renew to generate other cancer stem cells and mature aberrantly into the other cells that comprise the brain cancer tissue”, says lead investigator Peter Dirks, Hospital for Sick Children, Toronto, Canada. In healthy human brains, neuronal stem cells and their early progenitor cells express a marker called CD133. However, Dirks and colleagues found that tumours in human brains contained small subpopulations of cells that also expressed CD133 or other markers of mature brain cells. The investigators showed that tumours developed when cells that
had the CD133 marker were taken from human brain tumours and implanted into the brains of mice. Furthermore, the structure of the newly developed tumour was similar to that of the original tumour from which the cells had been isolated. When cells without CD133 marker were injected into the brains of mice, no tumours developed. The next step, Sheila Singh, lead author of the study, explains, is to look at the gene expression of the brain-tumour stem cells, so that new drugs or genetic therapies can be developed. According to Michael Clarke, University of Michigan, Ann Arbor, MI, USA, these findings have major implications for the diagnosis and treatment of brain cancers. “Identification of the brain-cancer stem cells should help in the quest for new
and more effective treatments”, he notes. “This is a very important study”, comments Sean Morrison (Howard Hughes Medical Institute, Ann Arbor, MI, USA), because it shows that some human brain-tumour cells are much more tumorigenic than others in vivo. “This is the best indication that at least some brain tumours follow the cancer stem-cell model that has already been demonstrated in the context of leukaemia and breast cancer. This should change the way we approach the treatment of brain tumours as it raises the possibility that we may be able to treat these tumours more effectively by specifically targeting the CD133+ fraction of tumorigenic cancer cells”, Morrison concludes.
Khabir Ahmad
One Pap smear of benefit in developing countries
http://oncology.thelancet.com Vol 6 January, 2005
31: 376–79). The researchers concluded that implementation of single lifetime Pap smear test in women aged 41–50 years could help control cervical cancer in developing countries. “As [most] cases of SIL and early invasive cancers are in the 41–50-year agegroup, it is important to target this population to get the maximum number of cervical cancer in treatable stages. Management of these SIL cases would prevent invasive carcinoma occurring at later stage in women older than 50 years”, says Das. “In a developing country, due to the financial burden and lack of cytologists, a single lifetime Pap smear at 41–50 years of age would be really helpful for detecting cervical cancer in a treatable stage and thus decreasing the morbidity and mortality.” However, Christian Marth (Medical University Innsbruck, Austria) says, “It is unethical to accept millions of deaths provoked by suboptimal screening. A once-in-a-lifetime Pap smear could
therefore be only one step in a right direction but should not be considered as the final goal”. But Thomas Julian (University of Wisconsin, Madison, WI, USA) comments, “Any screening is better than none, but only if there are resources to treat the disease”.
See page 43 for a Review on diagnosis and management of cervical SIL
Sanjit Bagchi
© NCI/Science Photo Library
Researchers from KG Medical University, Lucknow, India, have shown that in developing countries, where people cannot afford repeated Pap smears, one lifetime Pap at age 41–50 years could be sufficient for screening of cervical cancer. “[The] utility of single lifetime Pap smear screening [has been] postulated in past, but we tried to test the hypothesis in broader terms, accommodating women aged 41–50 years”, explains Vinita Das (KG Medical University, Lucknow, India). The researchers did a cytological analysis of Pap smears obtained from 31 032 women aged 16–70 years in India from April, 1971, to March, 2003. They found that 35% of women with cervical squamous intraepithelial lesions (SIL) and 30% with cervical cancer were aged 41–50 years. Moreover, the frequency of infection with human papillomavirus was also high in this age-group (Diagn Cytopathol 2004;
Frequency of human papillomavirus infection is high in 40–50-year-old women
9
Small subsets of cells initiate brain tumours Researchers have found that a small number of brain-tumour cells have the ability to initiate new tumours or to maintain tumour growth (Nature 2004; 432: 396–401). “These key cells—tumour-initiating cells or cancer stem cells—self renew to generate other cancer stem cells and mature aberrantly into the other cells that comprise the brain cancer tissue”, says lead investigator Peter Dirks, Hospital for Sick Children, Toronto, Canada. In healthy human brains, neuronal stem cells and their early progenitor cells express a marker called CD133. However, Dirks and colleagues found that tumours in human brains contained small subpopulations of cells that also expressed CD133 or other markers of mature brain cells. The investigators showed that tumours developed when cells that
had the CD133 marker were taken from human brain tumours and implanted into the brains of mice. Furthermore, the structure of the newly developed tumour was similar to that of the original tumour from which the cells had been isolated. When cells without CD133 marker were injected into the brains of mice, no tumours developed. The next step, Sheila Singh, lead author of the study, explains, is to look at the gene expression of the brain-tumour stem cells, so that new drugs or genetic therapies can be developed. According to Michael Clarke, University of Michigan, Ann Arbor, MI, USA, these findings have major implications for the diagnosis and treatment of brain cancers. “Identification of the brain-cancer stem cells should help in the quest for new
and more effective treatments”, he notes. “This is a very important study”, comments Sean Morrison (Howard Hughes Medical Institute, Ann Arbor, MI, USA), because it shows that some human brain-tumour cells are much more tumorigenic than others in vivo. “This is the best indication that at least some brain tumours follow the cancer stem-cell model that has already been demonstrated in the context of leukaemia and breast cancer. This should change the way we approach the treatment of brain tumours as it raises the possibility that we may be able to treat these tumours more effectively by specifically targeting the CD133+ fraction of tumorigenic cancer cells”, Morrison concludes.
Khabir Ahmad
One Pap smear of benefit in developing countries
http://oncology.thelancet.com Vol 6 January, 2005
31: 376–79). The researchers concluded that implementation of single lifetime Pap smear test in women aged 41–50 years could help control cervical cancer in developing countries. “As [most] cases of SIL and early invasive cancers are in the 41–50-year agegroup, it is important to target this population to get the maximum number of cervical cancer in treatable stages. Management of these SIL cases would prevent invasive carcinoma occurring at later stage in women older than 50 years”, says Das. “In a developing country, due to the financial burden and lack of cytologists, a single lifetime Pap smear at 41–50 years of age would be really helpful for detecting cervical cancer in a treatable stage and thus decreasing the morbidity and mortality.” However, Christian Marth (Medical University Innsbruck, Austria) says, “It is unethical to accept millions of deaths provoked by suboptimal screening. A once-in-a-lifetime Pap smear could
therefore be only one step in a right direction but should not be considered as the final goal”. But Thomas Julian (University of Wisconsin, Madison, WI, USA) comments, “Any screening is better than none, but only if there are resources to treat the disease”.
See page 43 for a Review on diagnosis and management of cervical SIL
Sanjit Bagchi
© NCI/Science Photo Library
Researchers from KG Medical University, Lucknow, India, have shown that in developing countries, where people cannot afford repeated Pap smears, one lifetime Pap at age 41–50 years could be sufficient for screening of cervical cancer. “[The] utility of single lifetime Pap smear screening [has been] postulated in past, but we tried to test the hypothesis in broader terms, accommodating women aged 41–50 years”, explains Vinita Das (KG Medical University, Lucknow, India). The researchers did a cytological analysis of Pap smears obtained from 31 032 women aged 16–70 years in India from April, 1971, to March, 2003. They found that 35% of women with cervical squamous intraepithelial lesions (SIL) and 30% with cervical cancer were aged 41–50 years. Moreover, the frequency of infection with human papillomavirus was also high in this age-group (Diagn Cytopathol 2004;
Frequency of human papillomavirus infection is high in 40–50-year-old women
9