Favorable treatment response of bevacizumab-combined chemotherapy for advanced or recurrent invasive mucinous adenocarcinoma of the lung: A retrospective observational study

Invasive mucinous adenocarcinoma (IMA) of the lung is a rare variant of adenocarcinoma characterized by abundant intracytoplasmic mucin within the tumor. Although IMA has poor sensitivity to conventional chemotherapy regimens used for non-small cell lung cancer, we observed a better response to the bevacizumab (BEV) regimen. In this retrospective study, we aimed to investigate the response to BEV-combined regimens in patients with IMA. Among 16 consecutive patients diagnosed with IMA between January 2016 and December 2020 at our institution and treated with systemic chemotherapy, seven patients were treated with BEV-combined regimens. The overall response rate to BEV-combined regimens was 85.7%, with six patients showing a partial response. The median progression-free survival was 6.1 months. One patient experienced respiratory failure, which was improved after administration of BEV-combined regimen. BEV-combined systemic therapy may have a favorable effect on advanced or recurrent IMA of the lung.

Perineal talc exposure and epithelial ovarian cancer risk in the Central Valley of California

Perineal talc use has been suggested as a possible risk factor for ovarian cancer based on its structural similarity to asbestos, a known human carcinogen. A population-based epidemiologic case-control study of epithelial ovarian cancer (EOC) was conducted in 22 counties of Central California that comprise the reporting area for 2 regional cancer registries. Telephone interviews were conducted with 256 cases diagnosed in the years 2000-2001 and 1,122 controls frequency-matched on age and ethnicity. The interview obtained information on demographic factors, menstrual and reproductive experience, exogenous hormone use, surgical history and family history of cancer. Questions on perineal talc use included frequency of use, duration of use and specific years when talc was used. Multivariate-adjusted odds ratio (OR) and 95% confidence intervals (CI) were derived from unconditional logistic regression. The OR for ever use of talc was 1.37 (CI = 1.02-1.85) compared to never users. However, no dose response association was found. Tubal ligation (TL) modified the effect of talc on EOC such that women with TL had an OR of 0.88 (CI = 0.46-1.68) associated with perineal talc use, whereas women with no TL had an OR of 1.54 (CI = 1.10-2.16). Talc use and EOC risk was highest in women with serous invasive tumors (OR = 1.77; CI = 1.12-2.81). This study provides some support for the hypothesis that perineal talc use is associated with an increased risk of EOC.

Active and passive tobacco smoking and the risk of borderline and invasive ovarian cancer (United States)

OBJECTIVE

A population-based case-control study was conducted to examine the hypothesis that active and passive tobacco smoking were associated with the risk of epithelial ovarian cancer.

METHODS

In-person interviews were obtained from 558 women with epithelial ovarian cancer (431 invasive, 127 borderline) and 607 population controls regarding active lifetime tobacco smoking, environmental tobacco smoke exposure in utero and during childhood, and other factors that may be related to the development of ovarian cancer.

RESULTS

No significant associations of ever or former tobacco smoking with the risk of invasive or borderline ovarian cancer were found, although long-term ex-smokers of 20 years or more were at significantly reduced risk of invasive cancer. Significant, positive dose-response relations of the number of cigarettes smoked per day and pack-years with the odds ratios for borderline cancer were evident. No association of active tobacco smoking with risk was found by histologic subtype of invasive ovarian cancer. Smokers were at significantly increased risk for borderline serous cystadenoma (OR: 1.91; 95% confidence intervals, CI: 1.09-3.34), but not for borderline mucinous cystadenoma. When we limited the analyses to current smokers, age-started smoking was significantly inversely related to the risk of invasive, but not borderline ovarian cancer. We found no association of gestational or childhood environmental tobacco smoke exposure with the risk of invasive or borderline ovarian cancer among never smokers.

CONCLUSIONS

These findings do not support an association of active tobacco smoking with the risk of invasive ovarian cancer. An increased risk of borderline serous cystadenoma among smokers must be viewed with caution.

Pronounced inhibition by a natural anthocyanin, purple corn color, of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-associated colorectal carcinogenesis in male F344 rats pretreated with 1,2-dimethylhydrazine

The potential of purple corn color (PCC), a natural anthocyanin, to modify colorectal carcinogenesis was investigated in male F344/DuCrj rats, initially treated with 1,2-dimethylhydrazine (DMH), receiving 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in the diet. After DMH initiation, PCC was given at a dietary level of 5.0% in combination with 0.02% PhIP until week 36. No PCC-treatment-related changes in clinical signs, body weight and food consumption were found. Incidences and multiplicities of colorectal adenomas and carcinomas in rats initiated with DMH were clearly increased by PhIP. In contrast, lesion development was suppressed by PCC administration. Furthermore, in the non-DMH initiation groups, induction of aberrant crypt foci by PhIP tended to be decreased by the PCC supplementation. The results thus demonstrate that while PhIP clearly exerts promoting effects on DMH-induced colorectal carcinogenesis, these can be reduced by 5.0% PCC in the diet, under the present experimental conditions.

The endometrium in breast cancer patients on tamoxifen

We restudied histologically and immunohistochemically 17 endometrial carcinomas, 2 malignant mixed tumors and 180 endometria with benign changes during or after tamoxifen therapy. The carcinomas were subtyped according to the 1994 WHO-classification. Endometrial biopsies were taken only if the endometrial thickness was > 8 mm sonographically, when a polyp was seen, or for postmenopausal bleeding. About half of the endometrial specimens showed simple or cystic atrophy, 55-76% had cystic-atrophic polyps or regressive hyperplasia. Depending upon the dose of tamoxifen, 7-19% (30 mg) to 27-36% (20 mg) showed moderate glandular proliferation. 20-33% had foci of mucinous, clear cell or serous-papillary metaplasia. 68-70% revealed diffuse extensive fibrosis of the endometrial stroma. None of 11 patients biopsied before starting tamoxifen therapy had advanced endometrial glandular proliferation in the second endometrial biopsy after tamoxifen treatment. None of the 19 endometrial neoplasms after tamoxifen therapy was of the endometrioid type: 11 were mucinous adenocarcinomas, 4 clear cell carcinomas, 2 serous-papillary carcinomas, one carcinosarcoma and one malignant Mullerian mixed tumor. The reasons for discrepancies between suspicious sonograms and endometrial atrophy are discussed.

Strong nasal carcinogenicity and genotoxicity of 1-nitroso-4-methylpiperazine after low dose inhalation in rats

Sprague-Dawley rats were exposed by inhalation to 1-nitroso-4-methylpiperazine (NMPz) vapor at 2.4 p.p.m. for 15 h/day for 74 days over a 7.5 month period. After a dose of 1.1 mg/day NMPz (total dose 340 mg/kg body wt) 10/10 animals developed tumors of the nasal cavity, mostly invasive muco-epidermoidal carcinomas; no such tumors were observed in sham-exposed controls. This high tumor yield was seen at an 80 times lower dose and a shorter latency period when compared with rat carcinogenicity studies reported earlier. The single cell microgel electrophoresis (Comet) assay was used to determine genotoxicity in target tissues. Short-term in vitro exposure of rat and human nasal epithelial tissues to NMPz caused genotoxic effects in cells of both species. Short-term in vivo exposure of rats to NMPz vapor for 1 h induced DNA damage in nasal epithelial cells. Our results revealed NMPz as a potent genotoxic nitrosamine in rat and human nasal cells, the carcinogenicity of inhaled NMPz vapor in rats being remarkably higher as compared with oral uptake.

Estrogen replacement therapy and risk of epithelial ovarian cancer

Estrogen replacement therapy (ERT), in common use among menopausal women, has been inconsistently related to risk of ovarian cancer. Part of the inconsistency may be due to differences in risk according to tumor histology. We therefore compared, within histologic groups, 367 cases of invasive epithelial ovarian cancer to 564 population controls on history of ERT practices. In multivariate logistic regression analyses adjusted for age, parity, oral-contraceptive usage, and other factors, the relative odds of nonmucinous ovarian cancer increased by 5.1% for each year of ERT use [i.e., adjusted odds ratio, 1.051; 95% confidence interval (CI), 1.01-1.09, as a multiplicative factor for each year of use]. In particular, compared to never use, women who employed ERT for a total of 5 years or longer had a relative odds of 2.03 (95% CI, 1.04-3.97) of having a serous carcinoma and 2.81 (95% CI, 1.15-6.89) of having an endometrioid carcinoma. Mucinous tumors were not associated with use. ERT usage may contribute to the development of nonmucinous types of ovarian cancer, and additional histology-specific analysis of this association in other studies is warranted.

Mucinous (colloid) carcinoma of urinary bladder following long-term cyclophosphamide therapy for Waldenstrom's macroglobulinemia

Carcinoma of the urinary bladder is a known complication of cyclophosphamide therapy. Almost all such cases have been transitional cell carcinomas. We report here the second example of an adenocarcinoma of bladder and the first purely mucinous (colloid) carcinoma of urinary bladder developing after long-term cyclophosphamide therapy. The patient, a 77-year-old woman, had been treated for Waldenstrom's macroglobulinemia for at least 24 years, during which time treatment for this disease varied from 50 to 100 mg per day. The disease terminated in acute myelogenous leukemia, and she died of severe disseminated intravascular coagulopathy associated with hypermacroglobulinemia. The mucinous (colloid) carcinoma of the urinary bladder was an incidental finding at autopsy.

High yields of K-ras mutations in intraductal papillary mucinous tumors and invasive adenocarcinomas induced by N-nitroso(2-hydroxypropyl)(2-oxopropyl)amine in the pancreas of female Syrian hamsters

Ductal adenocarcinoma, the most common form of pancreatic cancer in humans, is associated with activation of the K-ras oncogene in approximately 90% of cases. In contrast, K-ras mutations are found in < 50% of the relatively rare intraductal papillary mucinous tumor (IPMT), which arises in the main pancreatic ducts. Since both adenocarcinomas and IPMTs are believed to arise from ductal cells and progress through similar sequences of morphological changes (i.e. flat hyperplasia, papillary hyperplasia, atypia and carcinoma in situ), it is clear that such progression may not always necessitate activation of the ras oncogene. Experimentally ductal adenocarcinomas of the pancreas can be induced in the hamster model by a brief treatment with N-nitroso(2-hydroxypropyl)(2-oxopropyl)amine (HPOP), while IPMTs can be induced by a combined treatment with HPOP and orotic acid (OA) in an initiation/promotion schedule. Since animals are exposed to the carcinogen only once, initiated normal epithelium is expected to give rise to a wide spectrum of neoplastic and preneoplastic lesions, progression of which will depend on the extent of mutagenesis induced at initiation in the targeted cells. In order to investigate the role of K-ras in progression of IPMTs as compared with adenocarcinomas we have examined the presence of K-ras mutations in the above two types of experimentally induced pancreatic cancers, as well as in associated and preneoplastic lesions. K-ras mutations at codons 12, 13 and 61 were determined by a designed restriction fragment length polymorphism method using mismatched nested primers in 77 neoplastic and preneoplastic foci microdissected from 20 pancreases. Mutations were found in all foci of atypical hyperplasia, in carcinomas in situ and invasive cancer, whether such lesions originated in lobular tissue or in the main pancreatic duct. Mutations were also found in papillary hyperplasia and flat hyperplasia in small ducts and also in the main duct at high frequency. With one exception, all ras mutations were G-->A transitions at the second base of codon 12. Mutations were occasionally accompanied by excessive presence of the mutant ras allele or loss of the wild-type ras allele, events that were more frequent in atypical hyperplasia (5/17), carcinomas in situ (5/14), IPMTs (2/5) and invasive adenocarcinomas (2/5) than in flat hyperplasia (0/6) or papillary hyperplasia (2/18). Our results demonstrate that: (i) K-ras mutations, predominantly G-->A transitions, are present in all experimentally induced hamster tumors; (ii) the incidence of K-ras mutations in IPMTs is lower in humans than in the hamster model; (iii) advanced lesions in both adenocarcinomas and IPMTs were frequently associated with an excess of the mutant over the wild-type K-ras allele. It is likely that both adenocarcinomas and IPMTs induced chemically in the hamster model arise by mechanisms which involve early activation of K-ras. Such a mechanism seems to be applicable only in a fraction of human IPMTs.

Primary non-clear-cell adenocarcinomas of the vagina in older DES-exposed women

The association between in utero diethylstilbestrol (DES) exposure and the development of clear-cell adenocarcinoma of the vagina and cervix has been well described. However, non-clear-cell mucin-secreting adenocarcinoma in women with DES exposure has not been previously reported. We present two cases of non-clear-cell mucinous adenocarcinoma in women having a history of in utero DES exposure. These cancers were found in older women and were more advanced than the clear-cell adenocarcinoma associated with DES. Histologic features of these tumors were notable for atypical, irregular glands lined by endocervical, intestinal, and endometrioid epithelium. The development of non-clear-cell adenocarcinoma of the vagina in these patients may be associated with DES exposure in utero. Long-term surveillance of DES-exposed women may be warranted.

Attenuation of vasoactive intestinal peptide enhancement of colon carcinogenesis by ornithine decarboxylase inhibitor

The effects of combined administration of vasoactive intestinal peptide (VIP) and the ornithine decarboxylase (ODC) inhibitor, 1,3-diaminopropane (DAP), on development of colon tumors induced by azoxymethane (AOM), on ODC activity of the colon wall, and on the labelling index of colon epithelial cells were investigated in inbred Wistar rats. Rats received weekly subcutaneous injections of AOM for 10 weeks and subcutaneous injections of VIP every other day and drinking water containing DAP (2.5 milligrams) ad libitum until the end of the experiment at week 45. Administration of VIP significantly increased the incidence of colon tumors at week 45. It also resulted in significant increases in colon ODC activity and in the labelling index during administration of AOM, but not after its cessation. Administration of both DAP and VIP significantly reduced the enhanced colon carcinogenesis by VIP. The DAP significantly attenuated the VIP enhancement of colon ODC activity and of the labelling index during AOM administration. These findings indicate that ODC inhibition attenuated enhancement of colon carcinogenesis, and suggest that enhancement of colon carcinogenesis by VIP may be mediated through its polyamine biosynthesis.

Fertility therapy in the setting of a history of invasive epithelial ovarian cancer

A link between fertility drugs and epithelial ovarian cancer has been suggested by at least one case-control study, and by multiple case reports of such tumors developing following fertility drug therapy. We report the case of a woman with stage IC grade 1 mucinous epithelial ovarian cancer who died of recurrent disease shortly after receiving gonadotropin therapy for ovulation induction. The patient was initially treated with a staging procedure, unilateral salpingo-oophorectomy, and 3 courses of cytoxan and carboplatinum. Over the next 3 years she underwent 2 cycles of ovulation induction with exogenous gonadotropins. Five months after the second cycle, the patient presented with a bowel obstruction and extensive recurrence of disease. Two months later she died despite extensive surgical debulking, and cis-platinum and Taxol chemotherapy. Although a causal relationship between fertility therapy and ovarian cancer has not been established, this case report suggests ovulation induction may be inadvisable in a woman with a prior diagnosis of invasive epithelial ovarian cancer.

Alpha 1-antitrypsin as a biomarker in azoxymethane induced intestinal tumors in F344 rats

Alpha 1-antitrypsin (alpha 1AT) has been detected in several human tumors and is thought to be a marker of neoplastic change and progression. As the biology of azoxymethane (AOM) induced intestinal tumors in F344 rats has many characteristics of human intestinal tumors, we have investigated alpha 1AT expression in AOM induced rat intestinal tumors. Nine of 12 colonic carcinomas and 6/8 small intestinal carcinomas had alpha 1AT positive tumor cells. Only 1/11 colonic adenomas and 0/3 small intestinal adenomas contained alpha 1AT. Thus alpha 1AT is a marker of malignancy in this model. Inhibition of carcinogenesis by piroxicam and difluoromethyl ornithine inhibited alpha 1AT expression.

[Development and progression of undifferentiated carcinomas in the stomach]

Pathohistological studies of resected human stomachs and of experimental gastric cancers induced by ENNG have revealed that undifferentiated carcinomas arise at the neck region of glandular tubules both in the fundic and the pyloric mucosa, and tumor cells disclose the earliest invasion in the lamina propria by dripping from the glandular tubule. At earlier stages, the carcinoma cells tend to be confined to the middle level of the mucosa, and they extend to the horizontal direction of the mucosa. Most carcinomas at earlier stages comprise the diploid cell line. When tumors grow beyond a size of 2 cm in diameter in the mucosal layer, they begin to invade into the submucosal layer. As tumors grow, aneuploid and polyploid cancer cells arise in the diploid cell population. This is a kind of tumor progression. Aneuploid cancer cells disclose a more invasiveness, and they are ready to invade into the deep layer of the gastric wall. Scirrhous cancers are mostly composed of aneuploid cells, and it is suggested that small mucosal cancers which exclusively consist of aneuploid cells may become scirrhous cancers in a relatively short period.

[Growth rate of experimental colonic cancer in rats]

Colonic cancers were induced in rats by subcutaneous injection of 1,2-Dimethylhydrazine. Tumor growth patterns were estimated by means of a double contrast barium enema technique. Tumor growth was almost exponential and the average doubling time was 20 +/- 5 (m +/- S.D.) days, at which time three different types of tumor growth patterns: Constant type, decreasing type and reaccelerating type, were noted. Serial double contrast barium enema technique appeared to be an useful method of studying in vivo primary colonic cancer growth patterns in rats.

Effect of germanium on 1,2-dimethylhydrazine-induced intestinal cancer in rats

Through recent research, the trace element, germanium, was found to have an anticancer effect. The purpose of this research was to determine the effect of germanium on 1,2-dimethylhydrazine-induced intestinal cancer in rats. Ninety-six 8-week-old Sprague-Dawley male rats were divided into 4 groups, with 24 rats in each group. All received dimethylhydrazine, 20 mg/kg body weight, subcutaneously, once a week for 20 weeks. Except for one control group, the other three groups were subdivided into six groups and administered three different kinds of germanium (inorganic germanium, organic germanium, and natural organic germanium) one month before and during dimethylhydrazine treatment, and during dimethylhydrazine treatment, respectively. Twenty-four weeks after carcinogen exposure, all surviving animals were sacrificed and examined for intestinal tumors. The number and location of the tumors were recorded and the pathology examined. The incidence of intestinal cancer in the control group (dimethylhydrazine only) was 91 percent; in groups provided with inorganic germanium one month before and during dimethylhydrazine treatment, and during dimethylhydrazine treatment only, it was 91 and 78 percent; in groups provided with organic germanium one month before and during dimethylhydrazine treatment, and during dimethylhydrazine treatment only, it was 64 and 64 percent; in groups provided with natural organic germanium one month before and during dimethylhydrazine treatment and during dimethylhydrazine treatment only, it was 50 and 45 percent. From these results, the authors conclude that natural organic germanium has the best prevention effect for intestinal cancer in this animal model (P less than 0.01), followed by organic germanium (P less than 0.05). Inorganic germanium has no effect. However, there is no difference in the cancer prevention effect of germanium provided one month before and during dimethylhydrazine treatment, and during dimethylhydrazine treatment only.

Early gastric cancer induced by N-ethyl-N'-nitro-N-nitrosoguanidine in a cynomolgus monkey six years after initial diagnosis of the lesion

A signet ring cell carcinoma in the gastric antrum of a Cynomolgus monkey induced by N-ethyl-N'-nitro-N-nitrosoguanidine was sequentially studied by endoscopy, biopsy, and autopsy. The carcinoma was first detected on the angulus of the stomach at the 38th month as a slightly elevated lesion. Sixty-one months later this tumor was found to be still in the "early" (intramucosal) stage. Another, independent, initial gastric cancer was also discovered. This is the first example of an induced gastric carcinoma remaining in the "early" stage during a six-year follow-up period after the initial histologic diagnosis.

Effect of OK-432 on large-bowel carcinogenesis in rats

To examine the carcinogenetic and growth inhibitory effects of OK-432, large-bowel carcinoma was induced experimentally in rats by intrarectal injection of N-methyl-N-nitrosourea (MNU), and OK-432 was administered intradermally. Rats were sacrificed after six months and the large intestine was cut into serial sections. Histopathologic examination and analysis of the infiltrating mononuclear cells, using monoclonal antibodies, were performed. The average rate of carcinogenesis per rat was 15.7 +/- 8.5 in the MNU alone group (n = 10) and 8.3 +/- 3.5 in the MNU and OK-432 group (n = 6). The invasion was deeper than the muscularis propria in 16 out of 157 lesions (10.2 percent) in the MNU alone group and in one out of 50 lesions in the MNU + OK-432 group (2.0 percent) (P less than 0.05). When time of appearance of atypical glands or carcinomas were compared in the MNU alone and MNU + OK-432 group, carcinogenesis was found to be delayed in the MNU + OK-432 group. In the investigation of infiltrating mononuclear cells using monoclonal antibodies, there were increases in helper T cells in both the MNU alone and MNU + OK-432 groups, but there was little difference between the two groups. The results of this study suggest that the suppression of experimental carcinogenesis in the large bowel by the concomitant administration of OK-432 with MNU, may be due to the enhanced activation or prolonged activated state of immunocompetent cells, which appear via antigen recognition, by OK-432.

A study on the cell kinetics of the canine gastric mucosa by the cytofluorometric method: an evaluation of chemically induced gastric cancer

The cell kinetic alteration in the background mucosa of canine gastric cancer induced by N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) was evaluated by cytofluorometry in which the rate of S and G2 + M phase cell in gastric mucosal cells could be calculated, and a triphasic alteration was demonstrated; an initial reduction phase, an increase phase and a plateau phase with a high value. The initial reduction phase was caused by non-specific toxicity of ENNG as observed in drug induced gastric mucosal lesions, and subsequent increase and plateau phases originated from the action of ENNG itself to activate the mucosal turn-over and from histological changes in the background mucosa such as regenerative hyperplastic change after mucosal erosion and atrophic changes, sometimes including intestinal metaplastic change. Further, in comparison to carcinogenesis in chemically induced gastric cancer with and without a surfactant (Tween 60), it was suggested that one of the promotion effects of Tween 60 was closely related with activation of the mucosal turn-over.

[Colonic cancer induced by 1,2-dimethylhydrazine (DMH) in rats after partial colectomy]

Using colonic cancer induced by DMH as experimental model, carcinogenic rate in the rats with or without partial colectomy was compared in order to study the etiology of the local recurrence of large bowel cancer after radical resection and observe the influence of operative injury on carcinogenesis. Sixty five male Wistar rats were divided into two groups: 48 with a partial colectomy (group 1) and 17 controls (group 2). All were given subcutaneous injection of DMH 20 mg/kg weekly for twenty weeks. Then, some rats were killed on scheduled time, the others were sacrificed in the 29th week. The results showed that carcinogenic rate was 87.5% and 58.8% in groups 1 and 2 (P less than 0.05). The tumor number in anastomotic site in group 1 (57.1%) was much higher than that at corresponding site in group 2 (28.6%) (P less than 0.05). It is suggested that the trauma itself be one of the promoting factors for cancer recurrence in addition to implantation during operation, residual tumor, etc. Large bowel cancer induced by DMH in rats may be used as an experimental model in studying the same cancer in the human being. Furthermore, after having given DMH, large bowel cancer incidence of the rats in different intervals is described.

Induction of gastric carcinomas in nonhuman primates by N-ethyl-N'-nitro-N-nitrosoguanidine

N-Ethyl-N'-nitro-N-nitrosoguanidine [(ENNG) CAS: 63885-23-4] was administered to 5 Macaca monkeys (Macaca mulatta and M. irus) at a concentration of 200 or 300 micrograms/ml for 11-26 months in their drinking water. Gastric carcinomas in the pyloric region were observed in all 5 monkeys between experimental months 11 and 38. Histologically, these carcinomas were mainly poorly differentiated adenocarcinomas and signet-ring cell carcinomas, and a few moderately and well-differentiated adenocarcinomas were also found. The macroscopic and histologic appearances of these carcinomas were similar to those in humans.

Duration of ENNG administration and its effect on histological differentiation of experimental gastric cancer

An experimental trial in the induction of canine gastric cancers was conducted to study the relationship between the histological differentiation of adenocarcinoma and the duration of administration of the carcinogen, N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG). Twenty-three adult Beagle dogs were divided into three groups according to the duration of administration. Over 3 months administration, the total dose of ENNG per animal was 5.85 g, and only signet ring cell carcinomas and poorly differentiated adenocarcinomas were induced in the antral mucosa of the stomach in 5 of 10 recipients. During 6 and 9 months administration, the total doses per animal were 11.70 g and 17.55 g, well differentiated adenocarcinomas were observed in 12 of 13 animals and they coexisted with poorly differentiated adenocarcinomas and/or signet ring cell carcinomas. Atrophic hyperplastic gastritis and hyperplastic polyps were seen in the same stomach. The results of this study suggest that a greater amount of carcinogen, i.e., a higher total dose, is required for the development of well differentiated adenocarcinoma than for inducing poorly differentiated adenocarcinoma and signet ring cell carcinoma.

Enhancing effect of preadministration of carbon tetrachloride on methylazoxymethanol acetate-induced intestinal carcinogenesis

This study concerns the modifying effect of carbon tetrachloride (CCl4) on methylazoxymethanol acetate (MAM)-induced intestinal carcinogenesis in ACI rats of both sexes. Forty five animals were given CCl4 (0.5 ml/kg body weight) through a stomach tube, followed by an i.p. injection with MAM (25 mg/kg body weight) 24 hours after CCl4 treatment. The paired administrations were done once a week for 4 weeks and animals were observed until sacrifice 30 weeks later. Pretreatment with CCl4 caused not only early death from chemical toxicity of MAM but also an increase in small-bowel tumors.

Cell proliferation and cell loss in intramucosal signet ring cell carcinoma of canine stomachs induced by N-ethyl-N'-nitro-N-nitrosoguanidine

Signet ring cell carcinoma was induced in canine stomachs by N-ethyl-N'-nitro-N-nitrosoguanidine, and modes of cell proliferation and turnover in the carcinoma were studied by 3H-thymidine autoradiography in conjunction with morphometric analysis. From 2 to 15 months after the cessation of 8 months carcinogen treatment, carcinomas in an early stage were obtained. Most of the cancer tissues confined to the lamina propria showed a layered structure. This comprised three layers; the superficial and the deep layer were composed of signet ring cells, and the middle layer was composed of small round cells. The dogs were labeled with 3H-thymidine by s.c. injection and by local infusion of the celiac artery. Flash-labeled autoradiographs revealed that most 3H-thymidine incorporating cancer cells were located around the middle layer, with a small amount of mucin. Using a pulse labeling experiment, those labeled carcinoma cells were shown to migrate from the middle layer towards the surface. Morphometric analysis of the autoradiographs showed that the small cells in the middle layer migrated upwards and produced mucin to become full-blown signet ring cells by 5.5 days. In 15 days, most labeled cancer cells in the superficial layer had disappeared. This mode of cellular turnover appeared to mimic a cell renewal system of the normal gastric mucosa. If the cancer cells turn over in this way, the tumor must grow slowly, remaining as an intramucosal cancer for a relatively long period.

Induction of cancers in the intestine, liver and various other organs of rats by feeding mutagens from glutamic acid pyrolysate

The mutagenic compounds 2-amino-6-methyldipyrido[1,2-alpha:3',2'-d]imidazole (Glu-P-1) and 2- aminodipyrido [1,2-alpha: 3',2'-d]imidazole (Glu-P-2), which were isolated from a glutamic acid pyrolysate and are potent carcinogens in the liver and brown adipose tissue of mice, were found to be multipotent carcinogens in rats. These compounds were each given to F344 rats of both sexes at a concentration of 500 ppm in pellet diet for up to 24 months. Glu-P-1 induced tumors in the colon, small intestine, liver, Zymbal gland, clitoral gland and brain. Glu-P-2 produced tumors in the same sites at slightly lower incidence. The multipotent carcinogenicities of Glu-P-1 and Glu-P-2 in rats and mice suggest that heterocyclic amines present in cooked food may be important in the development of human cancer.

[Experimental minute gastric cancer induced by N-ethyl-N'-nitro-N-nitrosoguanidine in dogs]

150 micrograms/day of N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) was administered to a total of 8 dogs, (4 mongrels at age of 4 months and 4 beagles at age of 6 months) over a period of 8 months by Kurihara 's method. As a result of the administration, we found development of minute cancer as follows: In 3 animals, male beagle killed at 575th day, male mongrel at 1, 105th days and male mongrel at 1, 245th days, a total of 20 neoplasms of the stomach was found (18 early cancers and 2 advanced cancers). 13 of which being the minute cancer measuring less than 0.5 cm. There were 11 mucosal cancers and 2 submucosal cancers. When classified by the macroscopic pathological type, none was classified as the elevated type (I, IIa types), 5 lesions as the flat type (IIb type), and 8 lesions as the depression type (IIc type). Two lesions of submucosal cancer belonged to IIc type. When classified by the histological type, 2 were classified as papillary adenocarcinoma, 2 as well differentiated tubular adenocarcinoma, 1 as moderately differentiated tubular adenocarcinoma, 5 as poorly differentiated adenocarcinoma and 3 as signet-ring cell carcinoma.

Intestinal tumors in rats induced by mutagens from glutamic acid pyrolysate

2-Amino-6-methyldipyrido[1,2-a:3',3'-d]imidazole (Glu-P-1) and 2-amino-dipyrido[1,2-a:3',2'-d]imidazole (Glu-P-2), which were isolated from a glutamic acid pyrolysate, were proved to be multipotent carcinogens in rats, inducing tumors of the liver, intestine, ear duct and clitoral gland when administered orally to F344 rats. Intestinal tumors were produced for the first time in a series of experiments with heterocyclic amines. Details of the morphologic features of the intestinal tumors induced in F344 rats by Glu-P-1 and Glu-P-2 are described. There were no marked differences between the tumors induced by Glu-P-1 and Glu-P-2. Grossly, the tumors of the small intestine were recognized as papillary, polypoid or umbilicated masses. The most common tumors in the large intestine showed polypoid growth with a short stalk. Histologically, the intestinal tumors were classified as adenomas, adenocarcinomas, and mucinous carcinomas. Several adenocarcinomas were found adjacent to adenomas. Mucinous carcinomas developed only in the small intestine. Most of these tumors showed endophytic growth with extensive mucus production. Tumor tissue from the small intestine transplanted into the subcutis of the flank grew into tumors within 3 months.

Enhancing effect of dextran sulfate sodium on colorectal carcinogenesis by 1,2-dimethylhydrazine in rats

Four groups were used, each consisting of 24 male ACI rats. Group I received a single subcutaneous injection of 20 mg 1,2-dimethylhydrazine (DMH)/kg body weight and was fed on basal diet until the termination of the experiment. Group II received the same single injection as in group I and then, starting one week later, was fed the diet containing 1% dextran sulfate sodium (DS-M-1). Group III received an injection of 0.9% sodium chloride and then DS-M-1 diet. The control group was given neither DMH nor DS-M-1 diet. The experiment was terminated after 40 weeks. A significantly higher incidence of colorectal carcinoma was observed in group II, as compared with group I (P less than 0.02). These data demonstrate the enhancing effect of DS-M-1 on colorectal carcinogenesis.

Different dose-response relationships in the induction of different types of colonic tumors in Wistar rats by 1,2-dimethylhydrazine

Four groups of 21 male Wistar rats were given weekly subcutaneous injections of 1,2-dimethylhydrazine at a dose of 20 mg/kg body weight for 2, 4, 6 and 8 weeks, respectively, and 7 animals of each group were killed in weeks 24, 32 and 40. This treatment induced a clear dose-related increase in the total number of colonic carcinomas. The number of tubular adenocarcinomas, which were mostly located in the descending colon, was clearly dose-related, whereas the number of signet ring cell carcinomas, which developed in the ascending colon, was apparently dose-independent.

Genesis of 1,2-dimethylhydrazine-induced colon cancer. A light and electron microscopic study

Rats treated with 1,2-dimethylhydrazine (DMH) exhibited colonic mucosal dysplastic foci prior to the development of tumors. Ultrastructurally, these, as well as the cancers that subsequently developed, were characterized by alterations in plasma membranes and an increase in cytoplasmic ribosomal particles, principally in stem cells and their absorptive derivatives. Rare Kulchitsky cells appeared preserved, but the mucin-producing or goblet-cell elements were compressed and atrophic. In addition, nuclear aberrations were more pronounced in the cancer than in the dysplastic foci. The principal ultrastructural difference between the so-called well-differentiated and mucinous forms of DMH-induced cancers was the presence of frequent intracytoplasmic lumens in the mucinous form. Such structures represented the analogues of signet ring cells observed by light microscopy. This experimental model of human colonic cancer shows that the mucosal stem-cell and dysplastic lesions represent their cytogenetic and histogenetic progenitors.

A mode of incipient growth in chemically induced signet ring cell carcinoma of the canine stomach

A 31-month-old female mongrel dog was orally administered with 50 mg or 100 mg of N-nitrosobutylurea (NBU) in gelatin-capsule 3 times per week for 19 months with interposing periods of complete suspension. Thirty-four foci of signet ring cell carcinoma were found in the antral region of the stomach. The majority of the foci (31 foci) were early cancer, and the remaining foci were invasive cancer. In addition to these lesions, there was "a single gland cancer" in which a row of cancer cells was confined to a single gland. The whole gland was composed of two cell layers; the inner layer facing the lumen was normal gastric cells and the outer layer was atypical or neoplastic cells underlaid by the basement membrane. Mitosis was frequently observed on the bottom of the gland. Atypical or neoplastic cells seemed to mature gradually through a process of upward migration with increase in cytoplasmic Alcian blue-PAS and HID-AB positive mucin. Some of the cells rich in mucin moved into the lamina propria. The other cells remained in the flow of the regular cell renewal system of the normal gastric cells and reached the top of the gland. This observation revealed a mode of incipient gastric cancer growth, which starts and spreads within a single gland, before it invades the surrounding lamina propria.

Lysosomal enzymes in macrophages of colonic tumors induced in rats by 1,2-dimethylhydrazine dihydrochloride

Ten weekly doses of dimethylhydrazine (30 mg/kg) were given to rats to induce colonic tumors. Histochemical and electron cytochemical studies revealed a distinct pattern of lysosomal acid phosphatase and beta-glucuronidase activity in macrophages in the stroma of these neoplasms. A dramatic increase in the number of acid phosphatase-rich macrophages was present in adenomas when compared to that in normal colonic mucosa. Fewer numbers of these cells were seen in well-differentiated adenocarcinomas, and they were barely detectable in highly invasive mucinous adenocarcinomas. It is postulated that these macrophages may play a role in preventing the invasion of adenomatous neoplasms into the submucosa. Application of histochemical techniques to study macrophage lysosomal enzymes may prove a useful diagnostic tool in differentiation of human colonic tumors for prognostic evaluation.

Heterotransplantation of experimentally induced dog stomach adenocarcinoma to nude mice

Heterotransplantation of gastric adenocarcinoma, induced in dog by N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) has been attempted to nude mouse. Biopsied materials from Borrmann 3 type carcinoma, which showed signet-ring cell carcinoma at the subcardiac region of a beagle dog, were inoculated into the muscles of the hind legs of BALB/c-nu/nu nude mice. Serial transmission was obtained in 2 lives, so far 4-5 passages. The histological findings of the grafts were mainly poorly differentiated adenocarcinomas.

Histogenesis and growth pattern of 1,2-dimethylhydrazine-induced rat colon adenocarcinoma

The histogenesis and growth pattern of colon adenocarcinoma have been studied using 74 BD IX rats given 20 mg 1,2-dimethylhydrazine hydrochloride per kg, s.c., weekly from Day 11 to their 24th week and serially sacrificed with controls. Modifications in DNA synthesis activity and early tumor changes were sought on histological and radioautographic preparations of normal-appearing colon mucosa. All visible colorectal tumors were analyzed for size, site, and pathology. Chronic dimethylhydrazine treatments resulted in a simultaneous increase in the number of both total and tritiated thymidine-labeled cells in the glands of Lieberkühn. In addition, microscopic carcinomatous foci were observed after the 15th week, and the first macroscopic adenocarcinomas appeared in 24-week-old animals. Their number thereafter exponentially increased with time. A total of 252 macroscopic tumors were obtained, of which 14 were classified as signet ring cell carcinomas and 238 as adenocarcinomas. Among the latter, local invasion could be documented in 230, including the smallest. No benign polypcancer sequence could be demonstrated in this material. The average growth pattern of those adenocarcinomas could be adequately described by a Gompertz curve, with a short initial doubling time (e.g., 7.5 days in 1.0-cu mm tumors) that progressively increases with time (e.g., 59.6 days in 5000-cu mm tumors).

Transplantable colon tumors as chemotherapy screening models

A series of transplantable murine colon tumors have been developed from primary tumors induced by dimethylhydrazine. They are moderately- to well-differentiated adenocarcinomas which retain their histologic appearance and growth characteristics through successive transplant generations. The sensitivity of two tumor lines to 11 standard drugs is reported and some correlation shown with the sensitivity of human colorectal tumors to the same drugs. Therapeutic indices are low and each tumor has an individual pattern of sensitivity. The models have potential as secondary drug screening systems and for investigation of factors affecting drug sensitivity.

Dietary effects on chemical carcinogenesis in animal models for colon and liver tumors

Studies of dietary effects on chemical carcinogenesis in rats have demonstrated that colon tumor induction is enhanced by increased dietary fat intake or dietary deficiency of vitamin A in some but not all cases. The enhancing effect of a high-fat diet is augmented by lipotrope deficiency. Induction of hepatic tumors by several different carcinogens also is enhanced in rats fed a high-fat diet marginally deficient in lipotropes. The dietary effects may be exerted through alteration of metabolism of carcinogens, which has been demonstrated in lipotrope-deficient rats, through immunological mechanisms, which influence induction of colon tumors, or through effects on gastrointestinal bacteria and bile acid metabolism. Demonstration of dietary effects on carcinogenesis may require utilization of combined dietary stresses that alter metabolic loads but do not seriously impair growth.

[Immunologic results obtained with an experimental system oftransplantable colonic tumors. Possible applications of these results to human intestinal tumors]

Intestinal cancers, morphologically very close to human colo-rectal adeno-carcinoma, have been induced by dimethylhydrazine in inbred rats. Graftable lines have been obtained from 5 primary intestinal tumors, and 3 cell lines have been cultivated from the grafts. This model was used to demonstrate carcinofetal antigen(s) on the surface of the intestinal cancer cells. Circulating antibodies against tumor-associated antigen(s) have been found in tumor-bearing rats. Cancer enhancement was regularly observed when specific (tumor cells) and non-specific (B.C.G.) immunologic treatments were used to prevent or cure rat intestinal tumors. These results suggest that immunotherapy of human colo-rectal cancer might be hazardous.

Effect of BCG on dimethylhydrazine induction of colon tumors in rats

The effect of BCG injection into the colon wall on the induction of colon tumors by 1,2-dimethylhydrazine dihydrochloride (DMH) was assessed in male rats. Persistent, generalized BCG infection followed the intracolonic injection of 6.7 times 10(6) organisms in otherwise untreated rats. In rats given DMH (30 mg/kg/wk) intragastrically for 5 weeks and then infected with BCG, colon tumors developed at the same rate and in the same incidence as in uninfected rats, but more tumors were mucinous adenocarcinomas and metastasized to the abdominal lymph nodes. In a few rats with large, established colon tumors, the injection of BCG into tumors induced no apparent change in them when examined at autopsy 1-22 weeks later.

Effect of gastro-entero-pancreatic endocrine hormones on the histogenesis of gastric cancer in rats induced by N-methyl-N'-nitro-N-nitrosoguanidine; with special reference to development of scirrhous gastric cancer

One of five gastro-entero-pancreatic hormones, gastrin, serotonin, histamine, glucagon, and insulin, was intraperitoneally administered for a long period to the rats that received N-methy-N'-nitro-N-nitrosoguanidine. A frequent development of scirrhous carcinoma was demonstrated in the group treated with gastrin.

Immunologic aspects of 1, 2-dimethylhydrazine-induced colon tumors in rats

Investigation of immunologic aspects of colon tumors induced in rats by 1,2-dimethylhydrazine demonstrated that: 1) An antigen in an extract of colon tumors was not detected in the normal colon. It was related to antigens in rat fetuses and did not cross-react immunologically with carcinoembryonic antigen. 2) Mucinous adenocarcinomas of the colon were significantly associated spatially with lymphoid follicles.