Epidemiology of cancer of the cervix: global and national perspective

Cancer of the uterine cervix is one of the leading causes of cancer death among women worldwide. The estimated new cancer cervix cases per year is 500,000 of which 79% occur in the developing countries. Cancer cervix occupies either the top rank or second among cancers in women in the developing countries, whereas in the affluent countries cancer cervix does not even find a place in the top 5 leading cancers in women. The truncated rate (TR) in the age group 35-64 years in Chennai, India, is even higher (99.1/100,000; 1982-95) than rate reported from Cali, Colombia (77.4/100,000, 1987-91). The cervical cancer burden in India alone is estimated as 100,000 in 2001 AD. The differential pattern of cervical cancer and the wide variation in incidence are possibly related to environmental differences. Aetiologic association and possible risk factors for cervical carcinoma have been extensively studied. The factors are: Sexual and reproductive factors, socio-economic factors (education and income), viruses e.g., herpes simplex virus (HSV), human papillomavirus (HPV), human immunodeficiency virus (HIV) in cervical carcinogenesis and other factors like smoking, diet, oral contraceptives, hormones, etc. The accumulated evidence suggests that cervical cancer is preventable and is highly suitable for primary prevention. Sexual hygiene, use of barrier contraceptives and ritual circumcision can undoubtedly reduce cervical cancer incidence. Education, cervical cancer screening of high risk groups and improvement in socio-economic status can reduce cervical cancer morbidity and mortality significantly.

Cervical cancer screening in Tamilnadu, India: a feasibility study of training the village health nurse

Uterine cervical cancer is the most common malignancy among females in developing countries, including India. The success of cervical cancer screening programs in North America and Western Europe has been the result of centralized cervical-cytology screening. This is not possible in the villages (n = 17,000) of Tamilnadu where 58 percent of females in rural areas are illiterate, health infrastructure is mediocre, and cervical cytology is unknown. The present study was undertaken to examine if the village health nurse (VHN) could be trained quickly to identify a cervical abnormality by visual inspection so that we could 'down stage' the cancer to earlier stages, more amenable to treatment. VHNs also would be trained to take an adequate Pap smear. A total of 101 VHNs were trained in batches and returned to their villages. Within two years, 6,459 eligible women in the study area were screened. The agreement between the gynecologists and the VHNs in identifying cancer among those with abnormal cervix was 95 percent, and 80 percent of the Pap smears taken by VHNs were adequate by WHO criteria, making the feasibility study highly successful.

Comparative endoscopic study of primary gastric lymphoma vs. gastric carcinoma

The endoscopic records of 56 patients with primary gastric lymphoma and 120 patients with gastric adenocarcinoma (matched for age and sex) were compared with respect to site, extent, and type of tumor by endoscopy and biopsy results. Diagnosis of lymphoma was suspected on the basis of gross endoscopic appearance in 30 patients with 96% sensitivity. The endoscopic findings that achieved statistical significance in favor of lymphoma were extensive disease involving whole stomach, proximal stomach involvement, extension of tumor into duodenum, and the presence of volcano crater-like ulcers on polypoid lesions. Endoscopic biopsies were positive for lymphoma in 92% patients. Immunoperoxidase staining for leucocyte common antigen was positive in all the 24 patients with lymphoma where it was performed. We conclude that lymphoid origin of the stomach tumor may be suspected in one-half of the cases of primary gastric lymphoma by gross endoscopic findings. Multiple endoscopic biopsies are safe and highly sensitive and specific in the diagnosis of primary gastric lymphoma.

Preoperative multimodal therapy for locally advanced non-inflammatory breast cancer

The present study is a comparison of two sequential groups of advanced locoregional (T3, T4) non-inflammatory breast cancers. The first group was of 164 cases treated between 1965 and 1975 who received radiotherapy followed by surgery (Group I). The second group was of 211 cases treated between 1976 and 1984, who received radiotherapy combined with multidrug chemotherapy followed by surgery (Group II). The 5 and 10 year disease-free survival in the two groups are 47.5% vs 60.6% (P less than 0.005) and at 10 years 35.9% vs 44.1% respectively (P less than 0.005). Tumour sterility in the resected breast was more than doubled in the chemotherapy group (18.9% vs 42.1%). The impact of the addition of chemotherapy on survival was seen only in the node-positive group, the 5-year disease-free survival in node-positive cases being 44.7% compared to 28.2% when chemotherapy was not used (P less than 0.007). Remote metastases at 5 years in node positive cases also showed a significantly lower rate in the CT + RT arm against the RT-only arm (36.4% vs 54.3%) (P less than 0.005). The results clearly demonstrate the advantage of a multimodality approach in the management of Stage III breast cancers.

Influence of nitric oxide on agonist-mediated calcium mobilization in platelets

Recent studies have characterized endothelium-derived relaxing factor as nitric oxide. It appears to exert its effect by elevating intracellular levels of cyclic GMP. In this study we confirm that nitric oxide is a potent inhibitor of agonist-induced irreversible aggregation. At the concentrations tested nitric oxide effectively blocked thrombin-stimulated mobilization of cytosolic-free calcium in Fura 2-loaded platelets. In addition, nitric oxide prevented the inositol 1,4,5-trisphosphate-stimulated calcium rise in cytosolic calcium in saponin-permeabilized Fura 2-loaded platelets. Similar to the action of adenylate cyclase stimulators, nitric oxide facilitated lowering of calcium levels raised by the action of agonists. The specific mechanism by which it exerts its effect on intracellular levels of calcium is not clear.

Radiation, pepleomycin and hyperthermia in the therapy of locally advanced squamous cell carcinomas of the buccal mucosa

Oral squamous cell carcinoma is the commonest male (29%) and the second commonest female (18%) malignancy in South India. At first attendance 93% of the tumours are stage T3 or T4. They are essentially locoregional, remote metastases being rare (0.75%). Radiotherapy alone yields a poor survival (19% 5 year NED). Radiopotentiation by chemical sensitizers and cytotoxic drugs has been attempted since 1960, the best results being obtained by a combination of irradiation and bleomycin. There was, however, persistent failure in about 40% of cases. The present three-armed trial attempted to improve the results of radiotherapy and bleomycin by the addition of hyperthermia. A total of 101 T3 and T4 buccal squamous cancers were entered in the trial over a period of nearly three years. Entry closed in August 1987 and the last case was evaluated in October 1987, hence only response data are available. Hyperthermia did not confer any benefit.

Extracellular Na+, but not Na+/H+ exchange, is necessary for receptor-mediated arachidonate release in platelets

The effect of extracellular Na+ removal and replacement with other cations on receptor-mediated arachidonate release in platelets was studied to investigate the role of Na+/H+ exchange in this process. Replacement with choline+, K+, N-methylglucamine+ (which abolished the thrombin-induced pHi rise) or Li+ (which allowed a normal thrombin-induced pHi rise) significantly decreased arachidonate release in response to all concentrations (threshold to supra-maximal) of thrombin and collagen. This inhibition was not reversed by NH4Cl (10 mM) addition, which raised the pHi in the absence of Na+, but, on the contrary, NH4Cl addition further decreased the extent of thrombin- and collagen-induced arachidonate release, as well as decreasing 'weak'-agonist (ADP, adrenaline)-induced release and granule secretion in platelet-rich plasma. No detectable pHi rises were seen with collagen (1-20 micrograms/ml) and ADP (10 microM) in bis-(carboxyethyl)carboxyfluorescein-loaded platelets. Inhibition of thrombin-induced pHi rises was seen with 0.5-5 microM-5-NN-ethylisopropylamiloride (EIPA), but at these concentrations EIPA had little effect on thrombin-induced arachidonate release. At higher concentrations such as those used in previous studies (20-50 microM), EIPA inhibited aggregation/release induced by collagen and ADP in Na+ buffer as well as in choline+ buffer (where there was no detectable exchanger activity), suggesting that these concentrations of EIPA exert 'non-specific' effects at the membrane level. The results suggest that (i) Na+/H+ exchange and pHi elevations are not only necessary, but are probably inhibitory, to receptor-mediated arachidonate release in platelets, (ii) inhibition of receptor-mediated release in the absence of Na+ is most likely due to the absent Na+ ion itself, and (iii) caution should be exercised in the use of compounds such as EIPA, which, apart from inhibiting the Na+/H+ exchanger, have other undesirable and misleading effects in platelets.

Receptor- and phorbol-ester-mediated redistribution of protein kinase C in human platelets. Evidence that aggregation promotes degradation of protein kinase C

Translocation of Ca2+/phospholipid-dependent protein kinase (PKC) activity from cytosolic to membrane fractions was assessed in washed human platelet suspensions. Phorbol myristate acetate (PMA) induced a rapid loss of PKC activity from the cytosolic compartment in stirred platelets, which was not accompanied by measurable increases in membrane-associated activity, but was paralleled by a decrease in total cellular enzyme activity (cytosol plus membrane). When platelet aggregation was prevented by not stirring, (i) cytosolic activity was decreased by PMA, (ii) significant and maintained (1-15 min with PMA) increases in membrane-bound PKC were detected, and (iii) the decline in total enzyme activity was markedly slower. In stirred platelets, total and specific inhibition of PMA-induced aggregation by a fibrinogen-derived peptide (RGDS, i.e. Arg-Gly-Asp-Ser) promoted maximal increases in membrane-associated PKC in the presence of PMA and completely prevented the loss in cellular activity. Thrombin and collagen both induced a decrease in cytosolic PKC and a loss of total activity, but a significant rise in membrane activity was seen only with collagen; ADP had no detectable effect on enzyme distribution. These results demonstrate an agonist-induced redistribution of PKC and indicate that platelet aggregation may play an important role in the proteolysis, and hence persistence, of membrane-associated PKC. This observation has implications for the potency and duration of PKC-mediated responses induced by agonists and exogenous PKC activators.

The fibrinogen-derived peptide (RGDS) prevents proteolytic degradation of protein kinase C in platelets by inhibiting platelet aggregation

The effects of the fibrinogen-derived tetrapeptide, Arg-Gly-Asp-Ser (RGDS), on platelet activation processes was studied. At concentrations of 100-300 microM, RGDS completely prevented platelet aggregation induced by all the common platelet agonists, 'weak' and 'strong'. In agreement with earlier views on the aggregation-dependency of weak agonist-induced thromboxane synthesis and 5-hydroxytryptamine (5HT) secretion, RGDS (100-300 microM) inhibited these events induced by ADP, adrenaline and low concentrations of thrombin and collagen but not that induced by high concentrations of thrombin and collagen. 5HT secretion induced by the protein kinase C (PKC) activator, phorbol 12-myristate 13-acetate (PMA), was also not affected by RGDS, but proteolytic degradation of the translocated membrane-bound enzyme in PMA-treated platelets, due to the actions of the Ca2+-dependent protease (Ca-DP), was completely prevented such that in the presence of RGDS, sustained increases in membrane-bound PKC activity were observed. PMA alone caused only transient increases in membrane-bound PKC. This effect of RGDS was similar to the effect of E64-d, a recently described inhibitor of Ca-DP in platelets, or the effects seen with PMA in unstirred non-aggregating platelets. It is concluded that RGDS inhibits the actions of Ca-DP in platelets via inhibition of aggregation.

Effect of phorbol ester treatment on receptor-mediated versus G-protein-activator-mediated responses in platelets. Evidence for a two-site action of phorbol ester at the level of G-protein function

In platelets, and in several other cell systems, pre-treatment with protein kinase C activators such as phorbol 12-myristate 13-acetate (PMA) results in the inhibition of receptor-mediated responses, suggesting that protein kinase C may play an important role in the termination of signal transduction. In the present study, we have attempted to locate the site of action of phorbol ester by comparing thrombin-induced (i.e. receptor-mediated) platelet activation with that induced by guanosine 5'-[gamma-thio]triphosphate (GTP[S]) and NaF, two agents which by-pass the receptor and initiate platelet responses by directly modulating G-protein function. After a 10 s pre-treatment with PMA (16 nM), dense-granule secretion induced by thrombin (0.2 unit/ml), GTP[S] (40 microM) and NaF (30 mM) was potentiated, resulting in a greater than additive response to agent plus PMA. However, after a 5 min pre-treatment, thrombin-induced secretion alone was inhibited, whereas PMA plus GTP[S]/NaF-induced release remained greater than additive. [32P]Phosphatidate formation in response to all three agents, in contrast, was inhibited by 50-70% in PMA (5 min)-treated platelets. That secretion induced by these agents is a protein kinase C-dependent event was demonstrable by using staurosporine, a protein kinase C inhibitor which at concentrations of 1-10 nM inhibited (70-90%) PMA-induced as well as thrombin- and NaF-induced secretion and protein phosphorylation. In membranes from PMA-treated platelets, thrombin-stimulated GTPase activity was significantly enhanced compared with that in untreated membranes (59% versus 82% increase over basal activity). The results suggest that inhibition of receptor-mediated responses by PMA may be directed towards two sites relating to G-protein activation: (i) receptor-stimulated GTPase activity and (ii) G-protein-phospholipase C coupling. Furthermore, the lack of inhibition of NaF- and GTP[S]-induced secretion by PMA suggests that different mechanisms may be involved in thrombin-induced and G-protein-activator-induced secretion.

Na+/H+ exchange is not necessary for protein kinase C-mediated effects in platelets

The role of Na+/H+ exchange in protein kinase C-mediated effects in platelets was investigated by studying the effect of removal of extracellular Na+ ([Na+]e) on the different responses induced by phorbol 12-myristate 13-acetate (PMA) and 1,2-dioctanoylglycerol (diC8). None of the responses studied, namely, protein phosphorylation, translocation of enzyme activity to the membrane fraction, potentiatory and inhibitory effect on platelet activation ([Ca2+]i, arachidonate and granule release) showed an absolute dependence on [Na+]e. With the exception of dense-granule release, which was clearly potentiated by the removal of [Na+]e and showed a negative correlation with exchanger activity, the other effects of PMA and diC8 were not affected by [Na+]e removal. It is concluded that Na+/H+ exchange is not essential for protein kinase C activation in platelets.

Extracellular Na+ removal enhances granule secretion in platelets--evidence that Na+/H+ exchange is inhibitory to secretion induced by some agonists

The effect of extracellular Na+ [( Na+]e) removal on agonist-induced granule secretion in platelets in relation to [pH]i and [Ca2+]i changes was investigated. Substitution of [Na+]e with choline+ of K+ resulted in a significant enhancement of 5HT secretion induced by thrombin, collagen, U46619 and the protein kinase C activators, PMA and diC8. Increases in [Ca2+]i induced by thrombin and U46619 were slightly inhibited or unaffected in these buffers, but [pH]i increases induced by thrombin, U46619, PMA and diC8 were abolished and a drop in [pH]i (0.05 0.1 units below resting) was observed. Although preincubation with potassium acetate produced a big drop in [pH]i and greatly increased secretion with all the agonists, particularly in the absence of [Na+]e, clear evidence that [pH]i rises due to Na+/H+ exchange are inhibitory to secretion was obtained only with thrombin. Thus, (i) NH4Cl, which restored the increase in [pH]i in the absence of [Na+]e reduced the potentiated secretory response to thrombin, (ii) no increase in thrombin-induced secretion was observed when Na+ was replaced with Li+, which allowed a normal increase in [pH]i and (iii) ethyl isopropyl amiloride (EIPA) abolished the [pH]i rise and potentiated thrombin-induced secretion. With collagen and U46619, the results suggest that removal of [Na+]e per se rather than inhibition of Na+/H+ exchange results in enhanced secretion. It is concluded that [Na+]e per se and [pH]i elevations via Na+/H+ exchange both have important inhibitory roles in the control of platelet granule secretion.