Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Value, transparency, and inclusion: A values-based study of patient involvement in musculoskeletal research

Background

Patient and public involvement work (PPI) is essential to good research practice. Existing research indicates that PPI offers benefits to research design, conduct, communication, and implementation of findings. Understanding how PPI works and its value helps to provide information about best practice and highlight areas for further development. This study used a values-based approach to reporting PPI at a Research Unit focused on musculoskeletal conditions within a UK medical school.

Methods

The study was conducted between October 2019 and January 2020 using Gradinger’s value system framework as a theoretical basis. The framework comprises three value systems each containing five clusters. All PPI members and researchers who had attended PPI groups were invited to participate. Participants completed a structured questionnaire based on the value system framework; PPI members also provided further information through telephone interviews. Data were deductively analysed using a framework approach with data mapped onto value systems.

Results

Twelve PPI members and 17 researchers took part. Views about PPI activity mapped onto all three value systems. PPI members felt empowered to provide their views, and that their opinions were valued by researchers. It was important to PPI members that they were able to ‘give back’ and to do something positive with their experiences. Researchers would have liked the groups to be more representative of the wider population, patients highlighted that groups could include more younger members. Researchers recognised the value of PPI, and the study highlighted areas where researchers members might benefit from further awareness.

Conclusions

Three areas for development were identified: (i) facilitating researcher engagement in training about the value and importance of PPI in research; (ii) support for researchers to reflect on the role that PPI plays in transparency of healthcare research; (iii) work to further explore and address aspects of diversity and inclusion in PPI.

Long-term outcome of sacral nerve stimulation for faecal incontinence

AIM

Sacral nerve stimulation (SNS) is a minimally invasive treatment for faecal incontinence (FI). We report our experience of patients who have undergone SNS for FI with a minimum of 5 years' follow-up. This is a single centre prospective observational study with the aim to assess the long-term function of SNS.

METHOD

All patients implanted with SNS were identified from our prospective database. The date of implantation, first and last clinic follow-up, surgical complications and St Mark's incontinence scores were abstracted and analysed.

RESULTS

From 1996 to 2014, 381 patients were considered for SNS. Of these, 256 patients met the study inclusion criteria. Median age at implantation was 52 years (range 18-81). The ratio of women to men was 205:51. Indications were urge FI (25%), passive FI (17.9%) and mixed FI (57%). The median of the incontinence score at baseline was 19/24 and this improved to 7/24 at the 6-month follow-up. Of the total cohort, 235 patients received a medium-term follow-up (median 110 months, range 12-270) with a median continence score of 10/24 which was also confirmed at the telephone long-term follow-up on 185 patients (132 months, range 60-276).

CONCLUSION

This study demonstrates that SNS is an effective treatment in the long term. SNS results in an improvement of validated scores for approximately 60% of patients; however, there is a significant reduction of efficacy over time due to underlying causes.

Acceptability, effectiveness and safety of a Renew® anal insert in patients who have undergone restorative proctocolectomy with ileal pouch-anal anastomosis

INTRODUCTION

Restorative proctocolectomy has gained acceptance in the surgical management of medically refractive ulcerative colitis and cancer prevention in familial adenomatous polyposis. Incontinence following restorative proctocolectomy occurs in up to 25% of patients overnight. The Renew^® insert is an inert single-use device which acts as an anal plug. The aim of this study was to assess the acceptability, effectiveness and safety of the Renew^® insert in patients who have undergone restorative proctocolectomy. The device has yet to be assessed in patients who have undergone restorative proctocolectomy.

METHOD

This was a prospective study exploring the acceptability, effectiveness and safety of the Renew^® insert in improving incontinence in patients who had undergone restorative proctocolectomy. A total of 15 patients with incontinence were asked to use the Renew^® insert for 14 days following their standard care. The Incontinence Questionnaire-Bowels was used pre- and posttreatment to assess response and patients were asked to report the perceived acceptability, effectiveness and safety of the device at the end of the trial.

RESULTS

The device was acceptable to 8/15 (53%) of patients and was effective in 6/15 (40%). Only 2/15 (13%) of patients raised any safety concerns, and these were minor. The device was associated with a significant reduction in night seepage (P = 0.034).

CONCLUSION

In a small study, the Renew^® insert can be both acceptable and effective and is also associated with few safety concerns. It is also associated with significant reductions in night-time seepage.

A review of sacral nerve stimulation for faecal incontinence following rectal surgery and radiotherapy

AIM

Faecal incontinence may occur following rectal surgery and/or radiotherapy for rectal cancer. The aim of this paper was to review the evidence to support the use of sacral nerve stimulation (SNS) for patients with incontinence who had undergone rectal surgery or received rectal radiotherapy.

METHOD

A search was performed of PubMed, Medline and Embase. All studies which reported the outcome of SNS in patients who had undergone a rectal resection or radiotherapy were reviewed.

RESULTS

The first report of SNS following rectal surgery was in 2002. Since then seven further studies have described its effect in patients who have undergone anterior resection or pelvic radiotherapy. The total number of patients was 57. All studies were single group series, which ranged in size from one to 15 patients. The follow-up ranged from 1 to 36 months. The success of peripheral nerve evaluation ranged from 47% to 100%. Permanent SNS improved the symptoms and in some studies this was reflected in improved quality of life. The wide variation of patient factors, operations performed, the dose of radiotherapy given and time from operation makes interpretation of the results difficult.

CONCLUSION

Larger studies with better patient selection are needed to investigate the effect of SNS on incontinence following radiotherapy or rectal surgery.

A double-blinded randomized multicentre study to investigate the effect of changes in stimulation parameters on sacral nerve stimulation for constipation

AIM

Sacral nerve stimulation (SNS) may be offered to patients with constipation who have failed to improve with conservative treatment. The response to SNS is variable, with a significant loss of efficacy in some patients. An increased frequency of stimulation may improve the efficacy of SNS for faecal incontinence. This study aimed to see if alteration of the pulse width or frequency improved the outcome for those with constipation.

METHOD

Eleven patients with constipation currently being treated by SNS were recruited from three centres. They were randomized to five different protocols of stimulation each applied for 5 weeks. Group 1 used standard settings (pulse width 210 μs, frequency 14 Hz); in the other four groups (Groups 2-5) the pulse width and/or frequency were halved or doubled. Patients and investigators were blinded to the group allocation.

RESULTS

The Cleveland Clinic constipation score varied significantly between the five groups. Group 1 achieved the lowest score mean (± SD) 13.4 (± 4.4) (P = 0.03). The number of digitations per defaecation was the lowest in Group 4, 90 μs and 14 Hz (P < 0.01). No other variable changed significantly. Standard settings were the most preferred by the recruited patients.

CONCLUSION

Alteration of pulse width or frequency of stimulation had no significant effect on the outcome of SNS for constipation.

A pilot study to compare daily with twice weekly transcutaneous posterior tibial nerve stimulation for faecal incontinence

AIM

Posterior tibial nerve stimulation (PTNS) has been shown to improve faecal incontinence in the short term. The optimal treatment regimen is unclear with wide variations in protocol reported in the literature. The study aimed to assess two different regimens of transcutaneous PTNS and to establish whether increasing the frequency of stimulation increases the effectiveness.

METHOD

Thirty patients were randomized to receive once daily or twice weekly PTNS for a 6-week period. The treatment was carried out by the patient at home after instruction. The primary investigator was blinded to the patient allocation until the study had ended, at which point the symptoms were assessed. No further stimulation was given after 6 weeks and the patients were followed until their symptoms returned to the pre-stimulation state (baseline). The primary outcome measure was a change in the frequency of incontinent episodes.

RESULTS

Three patients in the daily group and none in the twice weekly group achieved complete continence. Only patients from the daily group showed a significant reduction in median (interquartile range) incontinent episodes per week from 5 (11.13) to 3.5 (4.31) (P = 0.025). There was no significant change in the frequency of defaecation nor in the ability to defer defaecation. Patients in the daily group experienced a significant improvement in the domains of lifestyle [2.2 (1.7) to 2.6 (1.65), P = 0.04] and embarrassment [1.7 (0.85) to 2.15 (0.4), P = 0.04] on the Rockwood Fecal Incontinence Quality of Life assessment. No adverse events were reported.

CONCLUSION

Transcutaneous PTNS can safely be used by the patient at home. Daily treatment may be more effective than twice weekly treatment. Larger studies are needed to investigate this further.

Immunological biomarkers: catalysts for translational advances in autoimmune diabetes

In a recent workshop organized by the JDRF focused on the 'Identification and Utilization of Robust Biomarkers in Type1 Diabetes', leaders in the field of type 1 diabetes (T1D)/autoimmunity and assay technology came together from academia, government and industry to assess the current state of the field, evaluate available resources/technologies and identify gaps that need to be filled for moving the field of T1D research forward. The highlights of this workshop are discussed in this paper, as well as the proposal for a larger, planned consortium effort, incorporating a JDRF Biomarker Core, to foster collaboration and accelerate progress in this critically needed area of T1D research.

Randomized double-blind crossover study of alternative stimulator settings in sacral nerve stimulation for faecal incontinence

Background

Sacral nerve stimulation is an established treatment for faecal incontinence. Nearly half of all patients experience loss of efficacy at some point. Standard reprogramming restores efficacy for some, but not all, patients. This study aimed to determine whether alternative stimulator settings would increase treatment efficacy.

Methods

Patients with sustained loss of efficacy were recruited from two international specialist centres. A number of alternative stimulation parameters were tested using a double-blind randomized crossover study design. Stimulation settings tested were pulse frequencies of 6·9 and 31 Hz, and pulse widths of 90 and 330 µs, compared with one standard setting of 14 Hz/210 µs. Treatment efficacy was evaluated using a disease-specific quality-of-life score (Fecal Incontinence Quality of Life Scale, FIQLS) and a bowel habit diary completed before randomization, during the study period and after 3 months of follow-up with one preferred setting.

Results

Fifteen patients were analysed. With one preferred setting, three of four subdomains in the FIQLS improved significantly. The mean(s.d.) total number of incontinence episodes dropped from 11·7(10·8) to 4·8(4·5) per 3 weeks (P = 0·011) and improvements were maintained after 3 months of follow-up. Optimal pacemaker settings were individual, but a trend towards highest patient satisfaction and improved treatment outcome was evident for high-frequency stimulation (31 Hz/210 µs), which was preferred by eight of the 15 patients.

Conclusion

Patients experiencing loss of efficacy can experience improvement if alternative pacemaker settings are tested. High-frequency stimulation (31 Hz/210 µs) was preferred by more than half of the patients, and improved treatment outcome was sustained at 3 months. Registration number: NCT01254695 (http://www.clinicaltrials.gov).

Mapping QTLs for resistance to the cyst nematode Globodera pallida derived from the wild potato species Solanum vernei

Resistance to the potato cyst nematode (PCN) species Globodera pallida, derived from the wild diploid potato species Solanum vernei, has been investigated. This source of resistance, which is effective against all of the major pathotypes of G. pallida and Globodera rostochiensis, has been assumed to be due to several genetic factors, but it has proved difficult to deploy effectively in breeding strategies for potato cultivars. Diploid and tetraploid potato populations segregating for 'vernei' resistance were analysed. At the tetraploid level, a bulk segregant analysis (BSA) approach was employed and detected AFLP markers linked to a resistance QTL on potato linkage group V. Conventional linkage analysis of a diploid population identified QTL on linkage groups V and IX. A marker linked to a QTL on linkage group V has been converted to a single-locus PCR-based marker, which can be used to detect the presence of the QTL in diploid and tetraploid potato germplasm. Moreover, there is evidence that one of the AFLPs detected by BSA appears to be specific to an introgressed segment of DNA from S. vernei. These results are compared with those obtained from other studies on resistance to the PCN species G. pallida.

Sediment evidence of early eutrophication and heavy metal pollution of Lake Mälaren, central Sweden

Lake Mälaren is the water supply and recreation area for more than 1 million people in central Sweden and subject to considerable environmental concern. To establish background data for assessments of contemporary levels of trophy and heavy metal pollution, sediment cores from the lake were analyzed. Diatom-inferred lake-water phosphorus concentrations suggest that pre-20th century nutrient levels in Södra Björkfjärden, a basin in the eastern part of Mälaren, were higher (c. 10-20 micrograms TP L-1) than previously assumed (c. 6 micrograms TP L-1). Stable lead isotope and lead concentration analyses from 3 basins (S. Björkfjärden, Gisselfjärden and Asköfjärden) show that the lake was polluted in the 19th century and earlier from extensive metal production and processing in the catchment, particularly in the Bergslagen region. The lake has experienced a substantial improvement of the lead pollution situation in the 20th century following closure of the mining and metal industry. The lead pollution from the old mining industry was large compared to late-20th century pollution from car emissions, burning of fossil fuels and modern industries.

Meeting the challenge of mandatory AIDS education for health care workers

AIDS is the number one health problem in our country today. To date, education is the only vaccine. In March 1988, the Washington State Legislature passed into law the Omnibus AIDS Bill, viewed nationwide as model AIDS legislation. This law mandated AIDS education in 1989 for approximately 110,000 Washington state licensed health care workers. In this article we describe the implementation of this requirement for 800 affected employees in a Seattle area community hospital. We describe audience response to the education requirement as well as to the AIDS education program developed at our hospital. Based on this experience, we have recommendations for other state legislative bodies considering similar legislation as well as for educators and other professionals who may be involved in the implementation of similar legislation.

The changing pattern of cancer mortality in South Africa, 1949-1979

The first paper in this series was published in 1975 and covered the period 1949 - 1969 for whites, coloureds and Asians in South Africa. This period is now extended to 30 years, from 1949 to 1979 inclusive, and includes data for urban blacks from 33 selected urban areas for the period 1968 - 1977. This information was superseded by data for all blacks, both rural and urban, in 1978. As this is available only for 2 years, the data are not included in this series, and all mention of blacks indicates information on urban blacks only. It is reassuring to know that mortality and geographical data for urban and rural blacks can now be separated from each other for comparative purposes, and that, in the future, transitional trends due to such striking phenomena as migratory labour and emigration to industrial areas can now be determined by the year. Finally, instead of expressing mortality rates per 100 000 of the population, a new method called the "cumulative rate or risk' is used, which is carefully defined. Changes in cancer patterns in all four major population groups are reflected graphically over the period 1949 - 1979 (blacks since 1968) by this method, and trends over this long period are discussed in terms of the frequency of cancers within each group, prognosis, aetiological factors and other related aspects.

Geographical distribution of certain cancers in South Africa, 1968-1972

The geographical distributions of six major causes of cancer mortality in South Africa have been analysed for three population groups: White, Coloured and Asian. Because of the lack of comparable data, the majority Black population is not included. Geographical patterns are compared and discussed in the light of findings from other countries. In several cases the potential for aetiological follow-up is demonstrated.

Geographical distribution of lung and stomach cancers in South Africa, 1968-1972

The geographical distribution of lung and stomach cancer among three races in South Africa (Whites, Coloureds and Asians) has been investigated for the years 1968-1972, and the patterns of the occurrence of cases of cancer have been tested stochastically and mapped both separately and together. Information was not available for the Black population. Distinct differences in the distribution of lung and stomach cancer were found. Possible explanations for these differences are discussed.

Eleven sites of cancer in black gold miners from Southern Africa: a geographic enquiry

The 5-year study of cancer in black gold miners, 1964-68, previously reported (Robertson et al., 1971) has now been extended for a separate 8-year period, 1972-79. This allows analyses of all cancers together and of 6 less common sites of cancer severally: lymphosarcomas, colon and rectum, leukaemia, stomach, pancreas and buccal cavity and also of those too rare to classify. The malignancies are considered by territory of origin of the gold miners. Lesotho miners have significantly fewer (P less than 0.05) tumours of the lymphatic and haemopoietic tissues and Natal miners have the highest incidence rates for 5 of the 6 sites (excluding leukaemia). A simple grouping method is applied to determine which of the 11 sites of cancer in the miners have similar distributions in their 10 territories of origin. The aetiological implications of clusters over space of certain sites of cancer are discussed. Finally, temporal change over the years 1964-79 shows a significant decrease overall (P less than 0.01) in cases of lymphosarcomas and colo-rectal cancers and an increase (P less than 0.05) in stomach cancer. The rare tumour, Kaposi's sarcoma, has also decreased significantly between the 2 periods studied.

Analyses of cancer incidence in black gold miners from Southern Africa (1964-79)

As an extension of an earlier study covering the 8-year period 1965-71 (t1), the incidence of cancer in black gold miners over a second 8-year period, 1972-79 (t2) has been investigated. The population again totalled 2.9 million man-years of employment, an average of 363,800 men per year. Of the 903 cancers found in t2, primary liver cancer accounted for 45.4%, oesophageal cancer 19.8%, cancer of the respiratory system 11.2% and bladder cancer 2.7%. Analysis of these 4 common cancers by country or region of origin of the miners confirms for the most part the patterns of incidence found in the earlier survey and consolidated rates are therefore presented for the full 16-year period, 1964-79 (t3). The spatial distribution of primary liver cancer within Mozambique and oesphageal cancer within Transkei have been investigated for the periods t1, t2 and t3 and temporal changes of rate have been examined by individual years from 1964 to 1979. The geographical gradient of incidence for cancer of the oesophagus in Transkei has become less marked during the second period of the survey and the crude incidence rate for primary liver cancer in gold miners from Mozambique has continued to drop throughout the period of the survey.

A comparison of cancer mortality rates in South Africa with those in other countries

Standardized mortality rates for eight major types of cancer (as well as for all types of cancer considered together) in four South African population groups are compared with each other and with rates in selected countries. Wide differences among the races in South Africa are displayed, and several rates are shown to parallel those in other population groups abroad. This lends support to the belief that socio-economic factors (rather than solely genetic factors) play the major role in cancer causation.

Cancer of the oesophagus and the use of tobacco and alcoholic beverages in Transkei, 1975-6

A large questionnaire-based sample survey over a period of 2 years has collected information on tobacco and alcohol use among young and old, male and female respondents in three regions of Transkei selected on the basis of having proved contrasts of incidence experience from oesophageal cancer. Results show significant gradients of social fabric and of customary usage of tobacco and alcohol across the three incidence regions. In particular the concept is supported of a synergistic relationship between tobacco and alcohol when both are used by one individual, with the major role being played by tobacco, especially when smoked in pipes. Stress is also laid on contrasts between old and young on the assumption that dynamic shifts of mortality may be expected to follow as the young of today alter the patterns of intake established by their elders.

The role of lysogeny in the modification of phage typing patterns of Staphylococcus aureus isolated from dairy cows

Strains of Staphylococcus aureus were isolated at a single sampling from cows in a dairy herd. When typed by phage most showed a complex pattern of lysis with group III and IV phages. Cross-spotting of strains showed great lytic activity and ten phages were isolated. The parent strains were lysogenized with these phages and the effect on the phage typing pattern of 202 daughter strains from 25 parent cultures was studied. Phage action was often blocked completely, with up to four being blocked on the one strain. Those most frequently blocked were phage 101, 117, 367 and 42D.

A spatial and temporal analysis of four cancers in African gold miners from Southern Africa

The pattern of cancer in African gold miners over the 8-year period 1964-71, comprising 2,926,461 man-years of employment was studied. Of the 1344 cancers found, primary liver cancer accounted for 52-8%, oesophageal cancer 12-1%, cancer of the respiratory system 5-4% and cancer of the bladder 4-8%. Analysis of the spatial distribution of these four cancers, both on subcontinental and local scale, showed distinct gradients of occurrence between areas of significantly higher and lower incidence than expected. In the case of primary liver cancer in Mozambique and oesophageal cancer in the Transkei, the spatial distribution reflects closely that found in the general resident population of each territory. The crude incidence rate of primary liver cancer in gold miners from Mozambique dropped sharply over the period of the survey.

The changing pattern of cancer mortality in South Africa, 1949-1969

Cancer mortality rates for Whites, Coloureds and Asians for the period of 1949 - 1969 have been analysed, and a changing pattern has been found. Some comparisons with other countries have been made, and the risk for each race group has been delineated for cancers at the commonest sites.

Smoking, drinking and oesophageal cancer in African males of Johannesburg, South Africa

A study of the smoking and drinking habits of 196 oesophageal cancer cases and 1064 control patients was made. All subjects were African males aged 35 years or more, drawn from a mainly urbanized population.It was found that tobacco smoking was prevalent and that pipe tobacco (used in pipes or in hand rolled cigarettes) was used more frequently than has been found in westernized countries. The drinking of alcohol was also a prevalent habit. Tribal affiliations were examined and all three of these factors showed differences between cases and controls. Further analysis of smoking and drinking together showed that only smoking had a positive association with oesophageal cancer, and this was also true after tribal adjustment had been made. A comparable analysis of data on Durban African males yielded similar findings.It was concluded that tobacco smoking was a powerful oesophageal insult but the authors were not able to show that alcohol was important in the development of oesophageal cancer in these people. Cigarette tobacco does not appear to be a significant oesophageal insult but pipe tobacco does, and the use of both these types of tobacco together may have a synergistic effect. Tribal affiliation has bearing on the smoking pattern.

The cancer pattern in African gold miners

The incidence of cancer among the African workers on the gold mines of South Africa has been studied for the period 1964-68. Considering the degree of selection to which they are subjected, the crude cancer rate was unexpectedly high.The most common cancers were those of the liver, the oesophagus, the respiratory system and the bladder. Geographical and tribal analysis showed that both liver and bladder cancers were predominantly found in Africans from Mozambique, while most of the oesophageal cancer occurred in Xhosas from the Transkei. The highest rate for cancer of the respiratory system was found in Africans from Natal, predominantly Zulu.The findings of this survey confirm those of previous South African surveys. The differences in cancer incidence are linked to both geographical area (physical environment), and to tribe, which may mean an association with tribal habit and custom. These factors need further investigation.

The cancer pattern in Africans at Baragwanath Hospital, Johannesburg

Material on African cancer cases admitted to Baragwanath Hospital, Johannesburg, over the years 1948-64 has been analysed, and it has been possible to obtain a useful incidence rate, a ratio study and a tribal analysis for purposes of comparison. The incidence rate, when compared to an earlier Johannesburg survey, showed a rise in oesophageal cancers for males and females. Both lung and prostate cancers showed rising rates in the men, while the female breast and cervix cancer rates remained relatively constant. Liver cancers had decreased in both sexes.

The cancer pattern in Africans of the Transvaal lowveld

An attempt has been made to study the Transvaal lowveld by district and tribe in relation to cancer patterns, and to compare these with those of bordering regions.The lowveld is divided into four districts, running from north to south. There appears to be a real increase in the frequency of liver and bladder cancers from north to south. The low cancer measurements in the most northern district (Letaba) are probably due to low cancer susceptibility. When cancers appear more common in the north, this is of interest seen against the very low cancer rates there. Both skin and musculo-skeletal tumours were commoner in the two northern districts in the ratio study and this was to some extent still true in the crude rate estimations.Tribally, the Sothos predominate in the north, the Swazis in the south, the Shangaans are evenly distributed through the area. It appears that Sothos are less cancer-susceptible than the other tribes. Looking at geographic and tribal differences together it would seem that liver cancer is related to physical environment whereas bladder cancer is associated with tribe.An attempt to compare contiguous areas is made in a ratio study comparison between highveld, lowveld and Lourenco Marques. Standardised cancer morbidity incidence rates from three surveys: Lowveld (1962-67), Johannesburg (1953-55), and Lourenco Marques (1956-61) are also compared. Generally speaking, the lowveld occupies a mid-position, both geographically and in terms of cancer patterns, between Lourenco Marques and the highveld-Johannesburg area.