Inflammation-associated pathologies in a case of prostate schistosomiasis: Implications for a causal role in prostate carcinogenesis.

BACKGROUND: Urogenital infection with Schistosoma haematobium is a risk factor for the development of squamous cell carcinoma of the urinary bladder. The pathophysiology is thought to be mediated in part by inflammation, cellular damage, and bladder regeneration induced by the parasitic infection. Herein, we report an unusual case of schistosomiasis of the prostate that was found concurrent with prostate adenocarcinoma in a radical prostatectomy specimen from a man in the United States. METHODS: The infecting Schistosoma species was characterized via histomorphology and acid-fast stain. The concurrent Gleason score 6 prostate cancer was assessed for ETS transcription factor ERG (ERG), phosphatase and tensin homolog (PTEN), p27, and p53 status using immunohistochemistry (IHC). Cellular proliferation and the presence of intermediate cells in prostatic atrophy were assessed via immunostaining for Ki67 and CK903, respectively. RESULTS: Histomorphology and acid-fast stain of the infecting species were consistent with S. haematobium. We classified the Gleason score 6 prostate adenocarcinoma via IHC as ERG positive, PTEN intact, p27 intact, and without p53 nuclear accumulation. The prostatic epithelium immediately adjacent to the schistosomiasis-related granulomatous inflammation was atrophic and accompanied by increased cellular proliferation and the presence of intermediate cells. Upon literature review, we determined that prostate schistosomiasis is associated with a young age of prostate cancer diagnosis and highly aggressive prostate cancer. CONCLUSIONS: This is a rare case of prostate schistosomiasis in the United States; however, prostate schistosomiasis occurs frequently in endemic areas. The patient had traveled to a Schistosoma-endemic region, which was the likely location of exposure to the parasite. To our knowledge, this is the first report of the association of proliferative inflammatory atrophy and intermediate cells with schistosomiasis of the prostate. We propose that prostate schistosomiasis may be considered as a risk factor for the development of prostate cancer in geographic regions where Schistosoma species are endemic.

Editorial: Best Practices in Surveillance of Barrett's Esophagus.

Endoscopic surveillance in Barrett's esophagus (BE) has numerous limitations and thus provides several opportunities for improving the effectiveness of our current surveillance strategies. Several risk stratification and prediction tools have been investigated to identify patients at highest risk for progression to esophageal adenocarcinoma (EAC). Persistence of non-dysplastic BE (NDBE) has been proposed as an indicator of lower risk of progression to EAC. This editorial highlights the variable results and methodologies in studies evaluating persistence of NDBE as a risk stratification tool in the surveillance of BE patients and provides guidance for optimizing outcomes in BE patients enrolled in surveillance programs.

Risk of malignant progression in Barrett's esophagus indefinite for dysplasia.

Barrett's esophagus is a well-recognized risk factor for esophageal adenocarcinoma. The natural history of Barrett's esophagus classified as 'indefinite for dysplasia' (IND) is poorly characterized. The aim of this study is to characterize the natural history of IND by determining the rate of neoplastic progression and identifying risk factors for progression. Patients from the University of Pennsylvania Health System pathology database and Barrett's esophagus registry with a diagnosis of IND between 2000 and 2014 were identified. Exclusion criteria included: (1) prior diagnosis of low-grade dysplasia (LGD), high-grade dysplasia (HGD), or esophageal adenocarcinoma (EAC); (2) presence of LGD, HGD, or EAC at the time of diagnosis of IND; and (3) lack of follow-up endoscopy after diagnosis. Patients with neoplastic progression were classified as having either prevalent disease (LGD, HGD, or EAC on surveillance biopsy within 12 months of IND diagnosis) or incident disease (LGD, HGD, or EAC on surveillance biopsy >12 months after IND diagnosis). One hundred six patients were eligible for analysis. Of 87 patients with follow-up endoscopy and biopsies within 1 year of IND diagnosis, 7 (8%) had prevalent disease (2 LGD, 4 HGD, 1 EAC). The prevalence of LGD was 2.3%, HGD was 4.6%, and EAC was 1.1%. Importantly, four of the seven prevalent (2 LGD, 2 HGD) cases were found to have dysplasia within 6 months of IND diagnosis. No demographic or endoscopic characteristics studied were associated with prevalent disease. Of the 106 IND patients, there were 66 patients without prevalent dysplasia with >1-year follow-up. Three (4.5%) progressed (1 to LGD after 12 months, 2 to HGD after 16.5 and 28 months), yielding an incidence rate for any dysplasia of 1.4 cases/100 person-years and HGD/EAC of 0.9/100 person-years. Risk factors for incident disease were smoking (p = 0.02) and Barrett's esophagus segment length (p = 0.03). IND is associated with considerable risk of prevalent dysplasia, especially within the first 6 months after diagnosis. However, the incidence of HGD/EAC is low and similar to previous studies of IND. These data suggest that IND patients should have repeat endoscopy within 6 months with careful surveillance protocols. Longer BE length and smoking history may help predict which patients are more likely to develop dysplasia, and therefore identify patients who may warrant even closer monitoring.

Prostate adenocarcinoma associated with prostatic infection due to Schistosoma haematobium. Case report and systematic review.

Schistosomiasis affects more than 240 million people worldwide, an infection which may cause urogenital manifestations including, among others, squamous bladder cancer and prostate involvement. We describe the first case of a prostate adenocarcinoma associated with prostatic Schistosoma haematobium infection occurring in Angola. Prostate carcinoma was suspected because of high levels of prostate-specific antigen. This observation prompted us to review the literature on schistosomiaisis with respect to genital pathology and prostate cancer. Described genital manifestations in men include funiculitis, epididymitis, granulomata of the seminal vesicles, testicular masses, and prostate lesions which may cause haematospermia and infertility. In contrast to bladder cancer, only 12 reports including the present case on 17 cases on prostate carcinoma associated with schistosomiasis have been published worldwide. The rarity of reports on prostate carcinoma associated with schistosomiasis is partly due to diagnostic constraints, and its incidence is underestimated. However, in emerging countries, the incidence of prostate cancer appears to increase mainly as a result of urbanization and improved access to health care where schistosomiasis prevalence is decreasing.

Fulminant cryptosporidiosis after near-drowning: a human Cryptosporidium parvum strain implicated in invasive gastrointestinal adenocarcinoma and cholangiocarcinoma in an experimental model.

In the present work, we report the characterization of a Cryptosporidium parvum strain isolated from a patient who nearly drowned in the Deule River (Lille, France) after being discharged from the hospital where he had undergone allogeneic stem cell transplantation. After being rescued and readmitted to the hospital, he developed fulminant cryptosporidiosis. The strain isolated from the patient's stools was identified as C. parvum II2A15G2R1 (subtype linked to zoonotic exposure) and inoculated into SCID mice. In this host, this virulent C. parvum isolate induced not only severe infection but also invasive gastrointestinal and biliary adenocarcinoma. The observation of adenocarcinomas that progressed through all layers of the digestive tract to the subserosa and spread via blood vessels confirmed the invasive nature of the neoplastic process. These results indicate for the first time that a human-derived C. parvum isolate is able to induce digestive cancer. This study is of special interest considering the exposure of a large number of humans and animals to this waterborne protozoan, which is highly tumorigenic when inoculated in a rodent model.

PRKAR1A overexpression is associated with increased ECPKA autoantibody in liver fluke-associated cholangiocarcinoma: application for assessment of the risk group.

Cholangiocarcinoma (CCA) associated with Opisthorchis viverrini (Ov) chronic infection is the most frequent primary liver cancer in Thailand, and current approaches to early diagnosis and curative treatments are largely disappointing. We hypothesize a role for protein kinase A (PKA) in Ov-induced CCA. First, we studied the PKA isozyme switching in the liver from the hamster CCA model using quantitative (q) PCR, in situ hybridization, and immunohistochemical and western blot analysis. Second, the presence of extracellular PKA (ECPKA) in CCA cell lines and their conditioned media was demonstrated by western blot and PKA activity assay. Third, we determined the association between PRKAR1A expression and serum ECPKA autoantibody in patients with CCA by ELISA. We demonstrated that an increased PRKAR1A expression is restricted to the biliary cells starting from week 1, with remarkable up-regulation when CCA has completely developed by week 24. The switching of the PKA regulatory subunit isoforms from PRKAR2B/PKAII to PRKAR1A/PKAI is significantly associated with cholangiocyte proliferation. Further, we observed that human CCA cell lines express PRKAR1A but not PRKAR2B and excrete ECPKA. Finally, ECPKA autoantibodies are detected in serum of patients with CCA, adenocarcinoma, and Ov infection with periductal fibrosis, but not from Ov-infected subjects without periductal fibrosis lesion and healthy controls. We conclude that PKA isozyme switching and the PRKAR1A/PKAI pathway might contribute to the induction of cholangiocyte transformation and proliferation in Ov-induced CCA. Overexpression of PRKAR1A leads to secretion of ECPKA which is associated with serum autoantibody that may constitute a biomarker for human CCA genesis.

Efficiency of diagnostic biomarkers among colonic schistosomiasis Egyptian patients.

The schistosomal parasite plays a critical role in the development of malignant lesions in different organs. The pathogenesis of cancer is currently under intense investigation to identify reliable prognostic indices for disease detection. The objective of this paper is to evaluate certain biochemical parameters as diagnostic tools to efficiently differentiate between colonic carcinoma and colonic carcinoma associated with schistosomal infection among Egyptian patients. The parameters under investigation are interleukin 2 (IL-2), tumour necrosis factor alpha (TNF-α), carcinoembryonic antigen (CEA) levels, tissue telomerase, pyruvate kinase (PK), glucose-6-phosphate dehydrogenase (G-6-PD) and lactate dehydrogenase (LDH) enzyme activities. The results revealed a significant elevation in the level of the tumour markers IL-2, TNF-α and CEA as well as the activities of LDH, telomerase and G-6-PD among non-bilharzial and bilharzial colonic cancer groups, with a more potent effect in bilharzial infection-associated colonic cancer. A significant inhibition in PK activity was recorded in the same manner as compared to normal tissues. The efficacy of this biomarker was also evaluated through detecting sensitivity, specificity, negative and positive predictive values. In conclusion, schistosomal colonic carcinoma patients displayed more drastic changes in all parameters under investigation. The combination of the selected parameters succeeded in serving as biomarkers to differentiate between the two malignant types.

Cytologic diagnosis of blastocystis hominis in peritoneal fluid: a case report.

BACKGROUND: Blastocystis hominis is the most common parasite identified in s worldwide. Although it is commonly identified in stool preparations, unusual to encounter B hominis in abdominal fluid. CASE: A 46-year-old woman presented with the clinical impression of acute peritonitis. The initial radiologic evaluation showed free air in the abdominal cavity and an abdominal mass. Abdominal fluid submitted for cytologic examination was diagnostic of acute inflammation with mixed bacteria and abundant cystlike forms of B hominis. The patient underwent an exploratory laparotomy that revealed a poorly differentiated adenocarcinoma involving her bowel and peritoneum. CONCLUSION: The present case highlights the unusual identification ofextraintestinal forms of B hominis in a peritoneal fluid sample from a patient with invasive, poorly differentiated adenocarcinoma and associated bowel perforation.

Consequences of Refusing Surgery for Esophageal Cancer: A National Cancer Database Analysis.

BACKGROUND: Given the potential morbidity of esophagectomy, patients may pursue other treatments. We sought to determine predictors and outcomes of esophageal cancer patients who refused esophagectomy. METHODS: The National Cancer Database (2004 to 2014) was queried for locally advanced esophageal cancer patients. A unique field allows identification of patients recommended to have surgery but who refused. Comparisons between the entire cohort and between propensity matched groups were performed using analysis of variance and χ2 tests. Survival was compared using Kaplan-Meier curves. Logistic regression was performed to identify predictors of refusing surgery. RESULTS: We identified 18,459 patients with esophageal cancer meeting criteria, including 708 (3.8) who were recommended but refused surgery. By multivariate analysis, elderly, female, nonwhite race, squamous histology, early year of diagnosis, absence of insurance, treatment at nonacademic centers, lower income, and clinical stage I/II predicted refusal of surgery. Median survival was worse for patients who refused surgery compared with patients undergoing surgery. Among propensity matched groups (n = 525 each), median survival was better for patients undergoing surgery versus patients who refused (32 versus 21 months, p < 0.001). CONCLUSIONS: Although patients may be reluctant to undergo esophagectomy for esophageal cancer, refusal of surgery when offered comes at the expense of decreased survival. These data allow for a discussion of alternative outcomes with those patients in the context of shared decision making.

A case of adenocarcinoma developed in the small intestine with chronic strongyloidiasis.

We experienced a case of intestinal strongyloidiasis complicated by jejunal carcinoma. A Japanese male in his 50s, who has a 7-year medical history of duodenal ulcers, complained of loss of appetite, nausea, vomiting and diarrhea. Computed tomography and gastroduodenal endoscopic examination revealed a stenosis of the duodenum. To remove the stenosis, gastric bypass surgery was performed. The pathological diagnosis of the resected jejunum was strongyloidiasis and well-differentiated adenocarcinoma with subserosal invasion and vascular infiltration. After administration of Ivermectin, Strongyloides stercoralis was not found in any biopsies or in the specimens of the intestine, which were resected due to cancer recurrence 2 years later. There are three possibilities for the reason of coexistence of S. stercoralis and adenocarcinoma: S. stercoralis caused the adenocarcinoma, S. stercoralis moved to the carcinoma, or just coincidence. Although it is difficult to prove a causal relationship between S. stercoralis and adenocarcinoma, this is the first report of adenocarcinoma developed in the jejunum with chronic strongyloidiasis. The number of nematode infections, including strongyloidiasis, is decreasing in Japan, although not worldwide. Therefore, it should be considered in patients with prolonged intestinal ulcers.

High association of Cryptosporidium spp. infection with colon adenocarcinoma in Lebanese patients.

BACKGROUND: The association between Cryptosporidium and human colon cancer has been reported in different populations. However, this association has not been well studied. In order to add new strong arguments for a probable link between cryptosporidiosis and colon human cancer, the aim of this study was to determine prevalence and to identify species of Cryptosporidium among Lebanese patients. METHODOLOGY AND PRINCIPAL FINDINGS: Overall, 218 digestive biopsies were collected in Tripoli, Lebanon, from three groups of patients: (i) patients with recently diagnosed colon intraepithelial neoplasia/adenocarcinoma before any treatment (n = 72); (ii) patients with recently diagnosed stomach intraepithelial neoplasia/adenocarcinoma before any treatment (n = 21); and (iii) patients without digestive intraepithelial neoplasia/adenocarcinoma but with persistent digestive symptoms (n = 125). DNA extraction was performed from paraffin-embedded tissue. The presence of the parasite in tissues was confirmed by PCR, microscopic observation and immunofluorescence analysis. We identified a high rate (21%) of Cryptosporidium presence in biopsies from Lebanese patients with recently diagnosed colonic neoplasia/adenocarcinoma before any treatment. This prevalence was significantly higher compared to 7% of Cryptosporidium prevalence among patients without colon neoplasia but with persistent gastrointestinal symptoms (OR: 4, CI: 1.65-9.6, P = 0.001). When the comparison was done against normal biopsies, the risk of infection increased 11-fold in the group of patients with colon adenocarcinoma (OR: 11.315, CI: 1.44-89.02, P = 0.003). CONCLUSIONS: This is the first study performed in Lebanon reporting the prevalence of Cryptosporidium among patients with digestive cancer. These results show that Cryptosporidium is strongly associated with human colon cancer being maybe a potential etiological agent of this disease.

Sigmoid colonic carcinoma associated with deposited ova of Schistosoma japonicum: a case report.

We report a case of sigmoid colonic carcinoma associated with deposited ova of Schistosoma japonicum. A 57-year old woman presented with a 10-mo history of left lower quadrant abdominal pain and a 2-mo history of bloody stools. She had a significant past medical history of asymptomatic schistosomiasis japonica and constipation. A colonoscopy showed an exophytic fragile neoplasm with an ulcerating surface in the sigmoid colon. During the radical operative procedure, we noted the partially encircling tumor was located in the distal sigmoid colon, and extended into the serosa. Succeeding pathological analysis demonstrated the diagnosis of sigmoid colonic ulcerative tubular adenocarcinoma, and showed deposited ova of Schistosoma japonicum in both tumor lesions and mesenteric lymph nodes. Three days after surgery the patient returned to the normal bowel function with one defecation per day. These findings reveal that deposited schistosome ova play a possible role in the carcinogenesis of colorectal cancer.

Colonic High-grade Tubular Adenomas Associated with Schistosoma japonicum.

We reported a case of sigmoid colonic high grade tubular adenomas associated with deposited ova of Schistosoma japonicum. A 76-year-old Japanese man was referred to our colonoscopy due to a positive fecal occult blood test. He had a medical history of schistosomiasis japonica. The colonoscopy revealed that there were two sigmoid colon polyps, approximately 8 mm in diameter. These were removed by endoscopic mucosal resection (EMR). Pathological examination revealed high grade tubular adenomas and deposited some ova of Schistosoma japonicum with severe fibrotic change and granuloma formation in the submucosal layer. Colonic schistosomiasis is a probable independent risk factor for the development of colorectal carcinogenesis.

Previous Exposure to the Fish Parasite Anisakis as a Potential Risk Factor for Gastric or Colon Adenocarcinoma.

Anisakiasis is a global disease caused by consumption of raw or lightly cooked fish contaminated with L3 Anisakis spp. larvae. High rates of parasitization of fish worldwide make Anisakis a serious health hazard. In fact, anisakiasis is a growing disease in countries such as Spain, Italy, and Japan, where consumption of raw/marinated fish is high. Some parasitic infections have been recognized as a causative factor for human cancer. Suggested mechanisms include chronic inflammation elicited by the parasite, and a possible tumorigenic effect from certain parasitic secretions. Anisakis can produce persistent local inflammation and granuloma, and larvae have been incidentally found in gastrointestinal (GI) tumors. Our aim was to discover possible differences in the prevalence of unnoticed or asymptomatic previous Anisakis infection in GI cancer patients compared with healthy individuals. Serum levels of specific antibodies against Anisakis antigens were used as a reliable marker of previous contact with their larvae. Ninety-four participants without a previous history of Anisakis infection were prospectively allocated into 1 of 2 groups: 47 patients with GI cancer and 47 controls. Specific IgE, IgA1, and IgG1 against the Anisakis recombinant antigens Ani s 1, Ani s 5, Ani s 9, and Ani s 10 were determined by an ELISA assay. The ratio of positivity to sIgA1, rAni s 1, or rAni s 5 was significantly higher in the cancer patients than in the controls (38.30% vs 6.38%, P < 0.001) and (42.55% vs 10.64%, P < 0.001, respectively). When disaggregated by type of tumor, the patients with gastric cancer showed a higher proportion of positive results for sIgA1 to rAni s 1 (P < 0.001), whereas a higher proportion of colon cancer patients were shown to be positive for sIgA1 to both rAni s 1 (P < 0.05) and rAni s 5 (P < 0.01). Earlier Anisakis infection might be a risk factor for the development of stomach or colon cancer.

Assessment of human colon cancer protein kinetics in vivo.

BACKGROUND: Malignancies enlarge because protein synthesis exceeds the rate of breakdown; however, the specific protein kinetic pattern remains unknown. Determining in vivo protein kinetic rates for a tumor may be useful for quantifying individual responses to a specific therapy. The aim of this study was to assess whether the growth of tumors is related to an increase in protein synthesis or an inhibition of protein breakdown. METHODS: Five patients (age, 59 +/- 3 years) with adenocarcinoma of the colon undergoing colonoscopy were studied. Tissue protein synthesis and breakdown rates were measured in vivo for both segments of colon cancer and adjacent normal-appearing colonic mucosa by using a primed, continuous infusion of 1(13)C leucine with tissue biopsy and quantitation of regional blood flow by laser Doppler flowmetry. RESULTS: Segments of colon cancer had a significantly (p < 0.05) greater rate of protein synthesis as quantitated by both the fractional rate of protein synthesis (Ca 45.4% +/- 5.0%/day versus nl mucosa 35.7% +/- 3.1%/day; mean +/- SEM) and by the tissue synthesis rate (Ca 69.4 +/- 9.0 versus nl mucosa 51.6 +/- 5.2 mumol/L leucine/day/100 gm tissue). Regional blood flow was significantly elevated in the cancer (Ca 110.9 +/- 5.8 versus nl mucosa 91.2 +/- 2.9 ml/min/100 gm), which contributed to commensurate rates of tissue breakdown (Ca 28.6 +/- 2.0 versus nl mucosa 28.2 +/- 2.4 mumol/L leucine/day/100 gm). CONCLUSIONS: These results illustrate that human colon cancers grow in vivo as a result of increases in protein synthesis. Furthermore, increases in regional blood flow limit the rate of tissue protein breakdown of colon cancer, thereby contributing to growth of the malignancy. These findings support the contention that therapeutic strategies aimed at negating this inherent increase in protein synthesis or limiting blood flow may effectively limit the growth of malignancies. This methodology may also provide an index for evaluating the effectiveness of future therapies aimed at reducing tumor growth for individual patients.

Amebiasis complicating carcinomas: a diagnostic dilemma.

Two black African women and one black American man had carcinomas of cervix, perineum, and sigmoid colon, respectively. In each of these patients, trophozoites of Entamoeba histolytica had invaded the surface of the tumor, and in some areas had invaded more deeply into the stroma between the tumor cells. Although it is well known that cutaneous amebiasis of anus, penis, vulva, and cervix can mimic squamous cell carcinoma, it may be, perhaps, less well known that carcinomas at these sites may be colonized by trophozoites of E. histolytica. In patients with amebiasis but without an associated carcinoma, a correct diagnosis of amebiasis spares the patient unnecessary and sometimes mutilating surgery. But a diagnosis of amebiasis, when there is an unrecognized underlying carcinoma, delays effective treatment of the carcinoma. A smear that establishes a diagnosis of cutaneous amebiasis, therefore, should be followed by biopsy to exclude or confirm an underlying carcinoma.

Patterns of Schistosoma haematobium egg distribution in the human lower urinary tract. III. Cancerous lower urinary tracts.

The distribution of S. haematobium eggs in urinary bladders containing tumors and removed at surgery has been studied; the majority of these tumors are well differentiated squamous cell carcinomas. The same three anatomic patterns of egg accumulation described in part I of this series (noncancerous lower urinary tracts) were found in these cancerous bladders, but, in addition, most of the tumors were surrounded by a collar of heavy S. haematobium egg deposition. The egg burdens in these collars were, on the average, twice the average egg burden in the remainder of the urinary bladder. These collars do not seem to be artifacts created by growth of the tumor and subsequent displacement of the adjacent normal tissue, creating a region of heavy egg concentrations; rather, these heavy S. haematobium egg concentrations seem to act as promoters of urothelial carcinogenesis.

The relationship between nasal myiasis and the prevalence of enzootic nasal tumours and the effects of treatment of Oestrus ovis and milk production in dairy ewes of Roquefort cheese area.

Infection by Oestrus ovis is common in Lacaune dairy ewes of Roquefort cheese area (Aveyron, France). It is believed by local breeders that there is a close relationship between nasal myiasis and the incidence of enzootic nasal tumour. In order to check these anecdotal reports, a serological survey was done on 658 breeding ewes before turn-out and 897 breeding and primiparous (hoggets) ewes at the end of the grazing season. By the time of sampling, it was clear whether the sheep were infected at the end of the winter or had been re-infected over summer. In April and September, 40.7 and 26.3%, respectively, were free of O. ovis infection, indicating that the autumn treatment was not completely effective and that O. ovis adult flies were circulating during the summer in many flocks. There were no differences in the incidence of adenocarcinoma between the groups indicating that there is no relationship between O. ovis infection and the presence of the cancer. Differences in milk production between the three groups were not statistically significant (Anova test P>0.05). In flocks where 1-5% of the ewes were infected or in non-infected flocks, ewes produced 3.6 and 8.56%, respectively, more milk than ewes from flocks where more than 5% of animals were infected. For primiparous ewes, the differences were of 8.5 and 12.24%.

Adenocarcinoma of the stomach: a multivariate analysis of clinical, pathologic and treatment factors.

We performed a retrospective prognostic study of 246 patients treated for adenocarcinoma of the stomach with curative intent over the period 1960-1984. Lesions of the cardia and gastro-esophageal junction were excluded. The study examined the prognostic influence of nine clinicopathologic and six treatment variables by univariate and multivariate analysis. Five-year survival rates (Kaplan-Meier) for TNM stages, IA, IB, II, IIIA, and IIIB were 88%, 80%, 55%, 30% and 9%, respectively. The Cox models of proportional hazards identified five independent variables predictive of death from gastric cancer: high TNM stage, metastatic involvement of four or more regional lymph nodes, poor differentiation of tumor, splenectomy and insufficient scope of regional lymph-adenectomy relative to the nodal stage (R minus N less than 1.5).