The role of aging in cancer incidence: an epidemiological study

JL, Cypriano M, Angel A, Toledo S. Diferenças clínicas, epidemiológicas e biológicas entre o câncer na criança e no adulto

O câncer representa hoje a primeira causa de morte por doença entre a população de faixa etária compreendida entre 1 e 21 anos nos Estados Unidos e em outros países economicamente desenvolvidos. No Brasil, esta doença figura como a terceira causa de morte por doença entre a população de faixa etária compreendida entre 1 e 14 anos, sendo já a primeira causa de óbito no município e no estado de São Paulo no grupo etário compreendido entre 5 e 14 anos, excluindo-se acidentes e causas externas. O objetivo deste artigo é informar a classe médica, principalmente a pediátrica, das particularidades do câncer infantil e de suas diferenças com as formas dos adultos, mais conhecidas e frequentes. Graças à moderna abordagem multidisciplinar, o câncer infantil pode atingir índices de cura de 60% a 70%, mas, para tal, é imprescindível o diagnóstico precoce. Portanto, é importante que toda a comunidade pediátrica mostre-se motivada e informada sobre os sinais e sintomas das neoplasias pediátricas, já que não dispomos de métodos de “screening” tão úteis e eficazes como para o controle do câncer do adulto.

Hydroxytyrosol inhibits chemokine C-C motif ligand 5 mediated aged quiescent fibroblast-induced stimulation of breast cancer cell proliferation

Cancer is an age-associated disease. Although the mechanisms of age-associated increase in cancer incidence are not completely understood, it is believed that the tumor stromal environment significantly influences epithelial malignancy. Fibroblasts are a major cell type in the stroma and, under normal conditions, fibroblasts reside in the quiescent state. Cellular quiescence is a reversible process where cells enter into the proliferative cycle and then exit back to quiescence. We have shown previously that quiescent fibroblasts lose their proliferative capacity as they age, and we defined this mode of cellular aging as chronological life span. Using conditioned media and co-culture experiments, results from this study show that normal human fibroblasts (NHFs) nearing the end of their chronological life span stimulate the proliferation of MB231 and MCF7 human breast epithelial cancer cells. Chemokine C-C motif ligand 5 (CCL5) expression was found to be approximately 8-fold higher in old compared to that in young quiescent NHFs, which correlated with an increase in the ERK1/2-cyclin D1 pro-proliferative pathway in MB231 cells. Conditioned media treated with anti-CCL5 antibody suppressed the activation of the ERK1/2-cyclin D1 pathway and proliferation of MB231 cells. Hydroxytyrosol, a dietary polyphenol and an active ingredient of olive, inhibited CCL5 expression in aging quiescent NHFs. This inhibition was associated with NHFs inability to activate the ERK1/2-cyclin D1 pathway and enhance proliferation of MB231 cells. These results show that fibroblasts nearing the end of their chronological life span promote proliferation of human breast epithelial cancer cells and dietary polyphenols inhibit this process.

Multiple malignant tumours in the elderly

Aging of the population and technical improvements may contribute to increase the possibility of multiple malignant tumours to be diagnosed. Over a period of 18 years, 2,749 consecutive autopsies of elderly patients were performed. In addition to macroscopic examination of every single organ, bone marrow and prostate were routinely stained and microscopically examined. One hundred and sixty-seven patients with multiple malignant tumours were found. Mean age was 81.1 years for females and 80.1 years for males. Mean interval between tumours was 2.4 years for females and 1.0 year for males. First tumours were most of the time diagnosed clinically (n = 121 vs. 46) whereas second tumours were diagnosed at autopsy (n = 121 vs. 46). Origin and metastastic sites of tumours were not different between the first and second tumour. Prostate and breast were the most frequent organs involved in males and females. Multiple malignant tumours in the elderly are not rare and the second tumour is frequently diagnosed after death despite occurring relatively soon after the diagnosis of the first tumour. Multiple malignant tumours may represent a significant clinical challenge leading to further diagnostic procedures and differentiated therapeutic approaches.

Young lung cancer patients in Japan: different characteristics between the sexes

BACKGROUND

Lung cancer in younger people is uncommon and has characteristics that distinguish it from cancer in older patients. The percentage of smokers among younger patients ranges from 40% to 50% in Asia to 90% in Western countries. The prognosis for young patients with this disease is controversial.

METHODS

Medical records of 91 young (40 years of age or younger) and 3,221 older (more than 40 years of age) Japanese patients with lung cancer were reviewed to compare smoking habits, distribution of histopathologic types, clinical stage, and survival.

RESULTS

Among female patients, only 39% were smokers in both age groups, whereas smokers were less common among the young male patients (84%) than the older male patients (95%) (p < 0.0001). Adenocarcinomas were diagnosed in 92% of the young and 73% of the older female patients (p = 0.021) versus only 71% and 42% of the corresponding male patients (p < 0.0001). There was no difference in tumor extent or survival between the two groups of female patients. In the male groups, advanced disease (stages IIIB and IV) was more common in the young patients (75%) than in the older patients (54%) (p = 0.0031), but there was no survival difference between the two groups.

CONCLUSIONS

Young male and female lung cancer patients in Japan have different characteristics from each other and from older patients of the same sex. Their survival did not differ from that of older patients.

The cellular ecology of progressive neoplastic transformation: a clonal analysis

A comparison was made of the competence for neoplastic transformation in three different sublines of NIH 3T3 cells and multiple clonal derivatives of each. Over 90% of the neoplastic foci produced by an uncloned transformed (t-SA') subline on a confluent background of nontransformed cells were of the dense, multilayered type, but about half of the t-SA' clones produced only light foci in assays without background. This asymmetry apparently arose from the failure of the light focus formers to register on a background of nontransformed cells. Comparison was made of the capacity for confluence-mediated transformation between uncloned parental cultures and their clonal derivatives by using two nontransformed sublines, one of which was highly sensitive and the other relatively refractory to confluence-mediated transformation. Transformation was more frequent in the clones than in the uncloned parental cultures for both sublines. This was dramatically so in the refractory subline, where the uncloned culture showed no overt sign of transformation in serially repeated assays but increasing numbers of its clones exhibited progressive transformation. The reason for the greater susceptibility of the pure clones is apparently the suppression of transformation among the diverse membership that makes up the uncloned parental culture. Progressive selection toward increasing degrees of transformation in confluent cultures plays a major role in the development of dense focus formers, but direct induction by the constraint of confluence may contribute by heritably damaging cells. In view of our finding of increased susceptibility to transformation in clonal versus uncloned populations, expansion of some clones at the expense of others during the aging process would contribute to the marked increase of cancer with age.

Hormesis and the antiaging action of dietary restriction

Hormesis refers to the often encountered phenomenon of a beneficial biological action from a factor or agent that is generally viewed as detrimental. Beneficial actions that have been observed include life span extension. It is proposed that life span extension in rodents by dietary restriction is an example of hormesis and that sustained moderate hyperadrenocorticism underlies this life prolongation. Evidence supporting this concept is presented. The possibility is also suggested that whenever hormesis leads to an extension of mammalian life span, it is likely that moderate hyperadrenocorticism plays a major role.

Patterns of X chromosome inactivation in sporadic basal cell carcinomas: evidence for clonality

BACKGROUND

Some basal cell carcinomas (BCCs) contain genetic mutations, suggesting that the lesion is composed of a monoclonal population of cells. Clonality, a distinguishing feature of neoplasia, can be inferred by referencing clonal markers such as the pattern of X chromosome inactivation. The X-linked human androgen receptor gene (HUMARA; GenBank) contains a polymorphic DNA marker that reliably illustrates the pattern of X chromosome inactivation in a tissue.

OBJECTIVE

Our purpose was to determine the clonality of sporadic BCCs by examining patterns of X chromosome inactivation.

METHODS

The patterns of X chromosome inactivation in paired samples of normal skin and sporadic BCCs from 24 women were compared by means of the HUMARA gene assay.

RESULTS

All samples from normal skin displayed random X chromosome inactivation, consistent with lyonization. In 15 of 25 tumor samples (60%), nonrandom X chromosome inactivation was detected, consistent with monoclonality.

CONCLUSION

At least some sporadic BCCs are composed of a monoclonal population of cells, strengthening the contention that a collection of mutations confers a growth advantage to this epithelial lesion.

Cell aging in vivo and in vitro

It has become a staple assumption of biology that there is an intrinsic fixed limit to the number of divisions that normal vertebrate cells can undergo before they senesce, and this limit is in some way related to aging of the organism. The notion of such a limited replicative lifespan arose from the often repeated observation that diploid fibroblasts cannot proliferate indefinitely in monolayer culture, and that the number of divisions before senescence is directly related to the in vivo lifespan of different species. The in vitro evidence is countered by estimates that the number of cell divisions in some organs of rodents and man are one or more orders of magnitude higher than the in vitro limit, with no indication of the degenerative changes seen in culture. Serial transplantation experiments in animals also exhibit many more cell divisions than the in vitro studies, with some indicating an indefinite replicative lifespan. I present evidence that vertebrate cells are severely stressed by enzymatic dispersion and sustain cumulative damage during serial subcultivations. The evidence includes large increases in cell size and its heterogeneity, reductions in replicative efficiency at low seeding densities, appearance of abnormal structures in the cytoplasm, changes in metabolism to a common cell culture type, continuous loss of methyl groups and reiterated sequences from DNA, and a constant rate of decline of growth rate with passage. This evidence is complemented by the reduction induced in the replicative life span of diploid cells by a large array of treatments which have different primary targets in the cells. The most consistent and general observation of cell behavior in aging animals, with only a few exceptions, is a reduction in the rate of cell proliferation. This reduction is perpetuated when the cells are grown in culture, indicating it is an enduring and intrinsic property of the cells rather than a systemic effect of the aging organism. A similar heritable reduction in growth rate can be induced in established cell lines by prolonged incubation at quiescence. The reduction can be exaggerated by subculturing the quiescent cells under suboptimal conditions, just as the effects of age are exaggerated under stress. The constant decline of growth rate that occurs during serial passage of diploid cells may represent a similar decay of cell function. I propose that the limit on replicative lifespan is an artifact that reflects the failure of diploid cells to adapt to the trauma of dissociation and the radically foreign environment of cell culture. It is, however, a useful artifact that has given us much information about cell behavior under stressful conditions. The overall evidence indicates cell in vivo accumulate damage over a lifetime that results in gradual loss of differentiated function and growth rate accompanied by an increased probability for the development of cancer. Such changes are normally held to a minimum by the organized state of the tissues and homeostatic regulation of the organism. The rejection of an intrinsic limit on the number of cell divisions eliminates the need for a cellular clock, such as telomere length, that counts mitoses. I offer a heuristic explanation for the gradual reduction of cell function and growth capacity with age based on a cumulative discoordination of interacting pathways within and between cells and tissues. I also make a case for the use of established cell lines as model systems for studying heritable damage to cell populations that simulates the effects of aging in vivo, and represents a relatively unexplored area of cell biology.

Microsatellite instability in lung cancer patients 40 years of age or younger

Lung cancer in the young, which has the characteristics of a higher incidence of adenocarcinoma, lower male-to-female ratio of the patients, and less frequent smoking history in the patients, may possibly be associated with genetic predisposition to cancers. We studied six microsatellite loci (D2S123, D3S659, D3S966, D5S346, WT1, and TP53) in 18 surgically treated lung cancer patients aged 25-40 years and nine control patients aged 62-74 to determine the presence of microsatellite instability (MSI) and to correlate its occurrence with clinicopathological characteristics. Of the 18 patients, 11 were female and seven were non-smokers. There were 15 adenocarcinomas and three squamous cell carcinomas, 15 (83%) of which had vascular invasion. MSI was positive in seven (39%) of 18 young patients and one (11%) of nine control patients. Moreover, MSIs in a half or more of six loci examined were demonstrated in five (28%) young patients, whereas no control patients showed such a high frequency of MSI. We observed no significant differences in clinical or pathologic parameters between cases with and without MSI. This result suggests that genetic factors play an important role in the development of lung cancer in young adults.

On the role of aging in carcinogenesis

Correlation coefficients for age-standardized incidence rates between cancers of the stomach, colon, rectum and lung over place (worldwide) and time (in Connecticut) vary from positive to negative values, indicating that these cancers are not caused by common environmental agents. Correlation coefficients for age-incidence patterns (the variation in age-specific rates with age) between these cancers, on the other hand, are all highly positive for both sexes. We conclude that the carcinogenic determinants that vary with age are common to the cancers studied and to both sexes, and distinct from the carcinogenic determinants that vary with place and time. For the cancers studied, incidence rates are negligible until age 30, at which time they increase dramatically and continue to increase at least until age 75. The rate of increase, however, diminishes continuously with advancing age after 30. We suggest that the role of aging in cancer incidence is determined by two components, one responsible for the dramatic rate increase beginning near age 30 and one responsible for the gradual diminution in that rate increase. The former may correspond to the activation of quiescent cells with damaged DNA or to the deactivation of DNA surveillance or repair or to impaired apoptosis, while the latter may correspond to the loss of cell division potential.

Evidence for cellular aging in long-term confluent cultures: heritable impairment of proliferation, accumulation of age pigments and their loss in neoplastic transformation

Previous experiments had shown that repeated rounds of prolonged growth constraint at confluence of NIH 3T3 sublines result in persistent changes in the growth behavior that are characteristic of cellular aging. These changes, which include an enduring decrease in the rate of proliferation in low density subcultures and a marked increase in neoplastic transformation, are here reproduced cumulatively over a 6 week period during which cultures are maintained in a single, continuous round of constraint at confluence. By testing multiple cultures at weekly intervals we show that the persistent reduction in exponential growth in low density subcultures is a property of the entire treated cell population that is first demonstrable in the cell population used here within a few days after the constraint of confluence is imposed. There is also a reduction in saturation density of cells subcultured from this early confluence which is reversed in longer term confluence when the cells become transformed. The reduction in exponential growth rate in serial subcultures becomes more pronounced in cells after longer periods of confluence. It is strongly manifest at 6 weeks when most of the cells have undergone neoplastic transformation. The transformation initially involves only a very small fraction of cells in a confluent culture, and is only detectable after 3 weeks of confluence. Beyond that time there is selective overgrowth of the transformed cells so they become the dominant element at 6 weeks. The very same cells from the 6 week cultures that have a reduced rate of growth when subcultured at low density, grow to higher saturation densities at confluence. The reduced growth rates are heterogeneously distributed among clones derived from the 6 week confluent cultures. Typical age pigment bodies appear in the cytoplasm of the cells after 3-4 days of confluence, and fill the cytoplasm at 2 weeks. They tend to enlarge into residual bodies at 3 weeks but largely disappear at 6 weeks when most of the cells are transformed. The results reinforce the conclusion that the prolonged constraint of confluence of these cells reproduces the major growth and morphological effects of cellular aging in the body.

Molecular staging of head and neck squamous carcinoma

The staging system of head and neck cancer is a Tumor-Node-Metastases system that was developed by the American Joint Committee on Cancer. The stage of the head and neck cancer defines the extent of the lesion and is determined by physical examination, radiologic studies, and pathologic examination. Accurate staging of head and neck cancer is critical since it will determine the treatment modalities used to cure the disease. Recent advances in the field of molecular genetics have allowed clinicians to detect occult cancer cells previously missed by physical examination and standard histopathologic techniques. Molecular assays are 500 times more sensitive in identifying cancer cells than standard techniques and provide more objective analyses with fewer sampling errors. Consequently, these techniques are currently being used to perform molecular staging of head and neck cancer patients. Preliminary results show that molecular staging will accurately identify those patients at significantly increased risk for recurrence of their head and neck cancer.

Primary myelodysplastic syndrome in children: the clinical experience in 33 cases

We describe the clinicomorphological features in 33 cases of primary myelodysplastic syndrome classified according to the FAB classification which presented to a single centre over a 12 year period. Presenting features were typically related to pancytopenia although hepatosplenomegaly and granulocytic sarcomas were far more prevalent than in the adult population. Morphological assessment of the peripheral blood and the bone marrow showed seven patients had refractory anaemia (RA), 13 patients had RA with excess of blasts (RAEB), nine patients had RAEB in transformation (RAEB-t) and four patients had chronic myelomonocytic leukaemia (CMML). The overall mean survival was short (9.9 months) in all the subgroups and the leukaemic transformation rate was high. None of the patients scored 0-1 according to the Bournemouth Scoring System; four patients scored 2 whereas 29 patients scored 3 to 4. We conclude that unlike adults, the myelodysplastic syndromes in children run an aggressive clinical course, irrespective of the FAB subtype, and the pathogenesis of these diseases in paediatric practice warrants scientific scrutiny. Intensive chemotherapy such as the one used in de novo-AML lead to complete remission in some children and these early results suggest that this should be the treatment of choice in paediatric MDS.

An altered repertoire of fos/jun (AP-1) at the onset of replicative senescence

With multiple divisions in culture, normal diploid cells suffer a loss of growth potential that leads to replicative senescence and a finite replicative capacity. Using quantitative RT-PCR, we have monitored mRNA expression levels of c-fos, c-jun, JunB, c-myc, p53, H-ras, and histone H4 during the replicative senescence of human fibroblasts. The earliest and the largest changes in gene expression occurred in c-fos and junB at mid-senescence prior to the first slowing in cell growth rates. The basal level of c-fos mRNA decreased to one-ninth that of the early-passage levels, while junB declined to one-third and c-jun expression remained constant. The decline in the basal c-fos mRNA level in mid-senescence should lead to an increase in Jun/Jun AP-1 homodimers at the expense of Fos/Jun heterodimers and may trigger a cascade of further changes in c-myc, p53, and H-ras expression in late-passage senescent fibroblasts.

The potential relationships between aging and cancer

The potential relationships between aging and cancer have received considerable attention in the scientific literature in recent years. While it is clear that the rates of most types of cancer increase with advancing age and that both the processes of aging and those of cancer are time dependent, an unequivocal relationship between the etiology of cancers and the mechanistic processes of aging has yet to be established. This article discusses the potential causal relationships between the processes of aging and the etiologies of most cancers.

Cancer risk assessment: the science that is not

Regulators have adopted the assumption of low dose linearity in cancer risk assessment, variously justified as scientifically correct and as responsible public health policy. Corollary assumptions are the one-molecule-one-hit hypothesis, the exclusion of no-effect thresholds, and the equivalency of response in experimental rodents and man. While our understanding of the carcinogenesis process remains tentative, these generalizations are not sustained by the limited scientific evidence available, not even as interim working hypotheses. In this light, they reflect a facile bureaucratic response to pragmatic demands borne of political perceptions, rather than the recognition of a complex and still opaque reality.

Free radicals in chemical carcinogenesis

During the past decade, remarkable progress has been made in our understanding of cancer-causing agents, mechanisms of cancer formation and the behavior of cancer cells. Cancer is characterized primarily by an increase in the number of abnormal cells derived from a given normal tissue, invasion of adjacent tissues by these abnormal cells, and lymphatic or blood-borne spread of malignant cells to regional lymph nodes and to distant sites (metastasis). It has been estimated that about 75-80% of all human cancers are environmentally induced, 30-40% of them by diet. Only a small minority, possibly no more than 2% of all cases, result purely from inherent genetic changes. Several lines of evidence confirm that the fundamental molecular event or events that cause a cell to become malignant occur at the level of the DNA and a variety of studies indicate that the critical molecular event in chemical carcinogenesis is the interaction of the chemical agent with DNA. The demonstration that DNA isolated from tumor cells can transfect normal cells and render them neoplastic provides direct proof that an alteration of the DNA is responsible for cancer. The transforming genes, or oncogenes, have been identified by restriction endonuclease mapping. One of the characteristics of tumor cells generated by transformation with viruses, chemicals, or radiation is their reduced requirement for serum growth factors. A critical significance of electrophilic metabolites of carcinogenes in chemical carcinogenesis has been demonstrated. A number of "proximate" and "ultimate" metabolites, especially those of aromatic amines, were described. The "ultimate" forms of carcinogens actually interact with cellular constituents to cause neoplastic transformation and are the final metabolic products in most pathways. Recent evidence indicates that free radical derivatives of chemical carcinogens may be produced both metabolically and nonenzymatically during their metabolism. Free radicals carry no charge but do possess a single unpaired electron, making the radical extremely reactive. That such forms may be important in the introduction of neoplastic transformation by chemicals from two lines of evidence. (1) Various molecules that inhibit the formation of free radicals, many of which are termed antioxidants, can inhibit the carcinogenic action of a variety of chemical carcinogens. (2) There are relatively specific metabolic reactions of certain chemical carcinogens, particularly of polycyclic hydrocarbons, for which it has been shown to proceed through free radical intermediates. In conclusion, free radical processes with direct effects on DNA can be proposed for a variety of human and animal carcinogens.(ABSTRACT TRUNCATED AT 400 WORDS)

Gerontology as oncology. Research on aging as the key to the understanding of cancer

It is widely appreciated that age is a powerful risk factor for cancer. This review considers two possible explanations for the exponential increase in most neoplasms in the elderly, arguing in favor of the idea that tumor progression proceeds at faster rates in older mice and older persons than in younger mice and younger persons. Three processes that alter the rate of aging, i.e., speciation, food restriction, and selective breeding, have parallel effects on cancer incidence. This suggests that the two processes are intimately connected. Elucidation of the mechanism(s) by which the aging process controls the rate of tumor development deserves high priority in experimental oncology. One such possible mechanism, the age-associated decline in immunologic defenses, is discussed at length in an attempt to rehabilitate the idea that a loss of immune function may contribute to the vulnerability of the elderly to cancer.

Biology of cancer and aging

The greatest risk factor for cancer is aging. Human cancer incidence increases exponentially with advancing age. Cancer growth rate and potential for metastatic spread may be influenced by age-specific change in host response. Because cancer and aging are, thus, inextricably linked, the American Cancer Society should encourage submission of research proposals that address the mechanisms of aging and how aging alters cancer development.

Surgical wound infection and cancer among the elderly: a case control study

Surgical wound infection occurs in fewer than 5% of operations. Nevertheless, it represents the second most common type of hospital-acquired infection and results in increased morbidity and mortality. As with all nosocomial infections, the rate of surgical wound infection increases with age. Patients over 65 years of age run an approximately 15% risk of surgical wound infection. Two-thirds of patients with invasive cancer other than non-melanotic skin cancer are aged 65 years and over. Over half of them are treated surgically for their cancer. Cancer and other chronic diseases have been cited as possible causes of the increased risk of nosocomial infection among the elderly. Using the Foothills Hospital Wound Study Data Base as the sampling frame, we conducted a case-control study of surgical wound infection and cancer among the elderly. Cancer was found not to be a risk factor for surgical wound infection. The results are discussed in relation to the role of immunity in both disorders.