Wenlong Chen

Mr. Wenlong Chen

University of the Witwatersrand, Johannesburg, South Africa
+1
orcid

Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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30 April 2022 in Cancer Epidemiology
Verified
Journal Article
Open access
MMMelitah Motlhale
Melitah Motlhale
FSFreddy Sitas
Freddy Sitas
DBDebbie Bradshaw
Debbie Bradshaw
WCWenlong Chen
Wenlong Chen
MSMwiza Gideon Singini
Mwiza Gideon Singini
ESElvira Singh
Elvira Singh
Kaposi's sarcoma (KS) has become a common AIDS-defining cancer in sub-Saharan Africa. Kaposi's sarcoma-associated human herpesvirus strongly modulated by HIV-related immune suppression are the principal causes of this cancer. No other risk factors have been identified as playing a strong role. HIV prevention programs and good coverage of antiretroviral therapy (ART) in developed countries resulted in a remarkable decline in HIV-KS incidence and better KS prognosis. By contrast, in sub-Saharan Africa, population ART rollout has lagged, but clinical studies have shown positive results in reduction of KS incidence and better KS prognosis. However, the effect of ART rollout in relation to population KS incidence is unclear. We describe the incidence of KS in sub-Saharan Africa, in four time-periods, (1) before 1980 (before HIV/AIDS era); (2) 1981-2000 (early HIV/AIDS era, limited or no ART coverage); (3) 2001-2010 (early ART coverage period); and (4) 2011-2016 (fair to good ART coverage period). We used KS incidence data available from WHO-International Agency for Research on Cancer (IARC) publications and the Africa Cancer Registry Network. National HIV prevalence and ART coverage data were derived from UNAIDS/WHO. A rapid increase in KS incidence was observed throughout sub-Saharan Africa as the HIV epidemic progressed, reaching peak incidences in Period 2 (pre-ART rollout) of 50.8 in males and 20.3 per 100 000 in females (Zimbabwe, Harare). The overall unweighted average decline in KS incidence between 2000 and 2010 and 2011-2016 was 27%, but this decline was not statistically significant across the region. ART rollout coincides with a decline in KS incidence across several regions in sub-Saharan Africa. The importance of other risk factors such as reductions in HIV incidence could not be ascertained.

11 May 2020 in Cancer Research
Verified
Journal Article
Open access
PDF file
MHMaxine Harlemon
Maxine Harlemon
OAOlabode Ajayi
Olabode Ajayi
PKPaidamoyo Kachambwa
Paidamoyo Kachambwa
MKMichelle S. Kim
Michelle S. Kim
CSCorinne N. Simonti
Corinne N. Simonti
JLJoseph Lachance
Joseph Lachance
Although prostate cancer is the leading cause of cancer mortality for African men, the vast majority of known disease associations have been detected in European study cohorts. Furthermore, most genome-wide association studies have used genotyping arrays that are hindered by SNP ascertainment bias. To overcome these disparities in genomic medicine, the Men of African Descent and Carcinoma of the Prostate (MADCaP) Network has developed a genotyping array that is optimized for African populations. The MADCaP Array contains more than 1.5 million markers and an imputation backbone that successfully tags over 94% of common genetic variants in African populations. This array also has a high density of markers in genomic regions associated with cancer susceptibility, including 8q24. We assessed the effectiveness of the MADCaP Array by genotyping 399 prostate cancer cases and 403 controls from seven urban study sites in sub-Saharan Africa. Samples from Ghana and Nigeria clustered together, whereas samples from Senegal and South Africa yielded distinct ancestry clusters. Using the MADCaP array, we identified cancer-associated loci that have large allele frequency differences across African populations. Polygenic risk scores for prostate cancer were higher in Nigeria than in Senegal. In summary, individual and population-level differences in prostate cancer risk were revealed using a novel genotyping array.Significance: This study presents an Africa-specific genotyping array, which enables investigators to identify novel disease associations and to fine-map genetic loci that are associated with prostate and other cancers.

6 February 2021 in BMC Cancer
Verified
Journal Article
Open access
PDF file
LMLactatia Motsuku
Lactatia Motsuku
WCWenlong Chen
Wenlong Chen
MMMazvita Molleen Muchengeti
Mazvita Molleen Muchengeti
MNMegan Naidoo
Megan Naidoo
TQTamlyn Mac Quene
Tamlyn Mac Quene
ESElvira Singh
Elvira Singh
Background: South Africa (SA) has experienced a rapid transition in the Human Development Index (HDI) over the past decade, which had an effect on the incidence and mortality rates of colorectal cancer (CRC). This study aims to provide CRC incidence and mortality trends by population group and sex in SA from 2002 to 2014.Methods: Incidence data were extracted from the South African National Cancer Registry and mortality data obtained from Statistics South Africa (STATS SA), for the period 2002 to 2014. Age-standardised incidence rates (ASIR) and age-standardised mortality rates (ASMR) were calculated using the STATS SA mid-year population as the denominator and the Segi world standard population data for standardisation. A Joinpoint regression analysis was computed for the CRC ASIR and ASMR by population group and sex.Results: A total of 33,232 incident CRC cases and 26,836 CRC deaths were reported during the study period. Of the CRC cases reported, 54% were males and 46% were females, and among deaths reported, 47% were males and 53% were females. Overall, there was a 2.5% annual average percentage change (AAPC) increase in ASIR from 2002 to 2014 (95% CI: 0.6–4.5,p-value < 0.001). For ASMR overall, there was 1.3% increase from 2002 to 2014 (95% CI: 0.1–2.6, p-value < 0.001). The ASIR and ASMR among population groups were stable, with the exception of the Black population group. The ASIR increased consistently at 4.3% for black males (95% CI: 1.9–6.7,p-value < 0.001) and 3.4% for black females (95% CI: 1.5–5.3,p-value < 0.001) from 2002 to 2014, respectively. Similarly, ASMR for black males and females increased by 4.2% (95% CI: 2.0–6.5,p-value < 0.001) and 3.4% (, 95%CI: 2.0–4.8, p-value < 0.01) from 2002 to 2014, respectively.Conclusions: The disparities in the CRC incidence and mortality trends may reflect socioeconomic inequalities across different population groups in SA. The rapid increase in CRC trends among the Black population group is concerning and requires further investigation and increased efforts for cancer prevention, early screening and diagnosis, as well as better access to cancer treatment.

3 January 2018 in Biopreservation and Biobanking
Verified
Journal Article
Closed access
WCWenlong Chen
Wenlong Chen
RKRobyn Kerr
Robyn Kerr
AMAndrew May
Andrew May
BNBabongile Ndlovu
Babongile Ndlovu
ASAnelisa Sobalisa
Anelisa Sobalisa
CVChantal Babb de Villiers
Chantal Babb de Villiers
Long-term storage of whole blood can affect the integrity of DNA if it is not done under optimal conditions. The aim of this study was to determine whether long-term storage (2–19 years) of whole blood samples at −30°C had a negative effect on the quality or quantity of genomic DNA that could be recovered at extraction. Genomic DNA was isolated from 2758 whole blood samples collected in 4 mL EDTA vacutainers from 1997 to 2012. DNA was extracted using the Qiagen ® FlexiGene ® DNA kit. The average storage duration at −30°C was 12 years. The quality and quantity of the isolated DNA were assessed using spectrophotometry (NanoDrop™), a fluorometric assay for double-stranded DNA (Qubit™), and agarose gel electrophoresis. The mean DNA yield per sample was found to be 114 μg from whole blood volumes that ranged from 0.5 to 4 mL. The mean A260/280 ratio and median A260/280 ratios were both 1.8. No correlation was found between the duration of storage and the total yield or the quality of DNA extracted. These data suggest that high-quality DNA can be extracted from whole blood samples that are stored at −30°C for up to 19 years.

9 June 2022 in Journal of Medical Virology
Verified
Journal Article
Open access
MSMwiza Gideon Singini
Mwiza Gideon Singini
ESElvira Singh
Elvira Singh
DBDebbie Bradshaw
Debbie Bradshaw
TRThendo Ramaliba
Thendo Ramaliba
WCWenlong Chen
Wenlong Chen
FSFreddy Sitas
Freddy Sitas
We reviewed the literature on the importance of selected anti‐high‐risk human papillomavirus (HR‐HPV) antibodies (namely, 16/18 and early oncoproteins E6 and E7) as potential serological markers for early detection of individuals at high risk of cervical cancer. We searched for studies in PubMed and Embase databases published from 2010 to 2020 on antibodies against HR‐HPV E6 and E7 early proteins and cervical cancer. Pooled sensitivity and specificity for HPV16 and HPV18 antibodies were calculated using a bivariate hierarchical random‐effects model. A total of 69 articles were identified; we included three studies with 1550 participants. For the three HPV16/18 E6 and E7 antibody tests, enzyme‐linked immunosorbent assay‐based assays had a sensitivity of 18% for detecting CIN2+ (95% confidence interval [CI]: 15–21) and a specificity of 96% (95% CI: 92–98), for slot‐blot, sensitivity was 28.9% (95% CI: 23.3–35.1) and specificity was 72% (95% CI: 66.6–77.0) for detecting CIN2+, and for multiplex HPV serology assay based on a glutathione S ‐transferase, sensitivity was 16% (95% CI: 8.45–28.6) and specificity was 98% (95% CI: 97–99) for detecting invasive cervical cancer. HR‐HPV16/18 E6 and E7 serological markers showed high specificity, but sensitivity was suboptimal for the detection of cervical cancer in either population screening settings or as point‐of‐care screening tests.

11 February 2021 in PLOS ONE
Verified
Journal Article
Open access
PDF file
WMWitness Mapanga
Witness Mapanga
Shane NorrisShane Norris
Shane Norris
WCWenlong Chen
Wenlong Chen
CBCharmaine Louise Blanchard
Charmaine Louise Blanchard
AGAnita Graham
Anita Graham
MJMaureen Joffe
Maureen Joffe
Background: Lung cancer is the highest incident cancer globally and is associated with significant morbidity and mortality particularly if identified at a late stage. Poor patient outcomes in low- and middle-income countries (LMIC’s) might reflect contextual patient and health system constraints at multiple levels, that act as barriers to prevention, disease recognition, diagnosis, and treatment. Lung cancer screening, even for high-risk patients, is not available in the public health sector in South Africa (SA), where the current HIV and tuberculosis (TB) epidemics often take precedence. Yet, there has been no formal assessment of the individual and health-system related barriers that may delay patients with lung cancer from seeking and accessing help within the public health care system and receiving the appropriate and effective diagnosis and treatment. This study aimed to derive consensus from health-system stakeholders in the urban Gauteng Province of SA on the most important challenges faced by the health services and patients in achieving optimum lung cancer management and to identify potential solutions. Methods: The study was undertaken among 27 participant stakeholders representing clinical managers, clinicians, opinion leaders from the public health sector and non-governmental organisation (NGO) representatives. The study compromised two components: consensus and engagement. For the consensus component, the Delphi Technique was employed with open-ended questions and item ranking from five rounds of consensus-seeking, to achieve collective agreement on the most important challenges faced by patients and the health services in achieving optimal lung cancer management. For the engagement component, the Nominal Group Technique was used to articulate ideas and reach an agreement on the group’s recommendations for solution strategies and approaches. Results: Public health sector stakeholders suggested that a lack of knowledge and awareness of lung cancer, and the apparent stigma associated with the disease and its risk factors, as well as symptoms and signs, are critical to treatment delay. Furthermore, delays in up-referral of patients with suspected lung cancer from district health care level were attributed to inadequate knowledge arising from a lack of in-service training of nurses and doctors regarding oncologic symptoms, risk factors, need for further investigation, interpretation of x-rays and available treatments. At a tertiary level, participants suggested that insufficient availability of specialised diagnostic resources (imaging, cytological and pathological services including biomolecular assessment of lung cancer), theatres, cardiothoracic surgeons, and appropriate therapeutic modalities (chemotherapeutic agents and radiation oncology) are the main barriers to the provision of optimal care. It was suggested that a primary prevention programme initiated by the government that involves private-public partnerships may improve lung cancer management nationally. Conclusions: Considerable barriers to the early identification and treatment of lung cancer exist. Finding solutions to overcome both individual and health-system level obstacles to lung cancer screening and management are vital to facilitate early identification and treatment, and to improve survival. Furthermore, research on inexpensive biomarkers for asymptomatic disease detection, the introduction of diagnostic imaging tools that utilise artificial intelligence to compensate for inadequate human resources and improving clinical integration across all levels of the healthcare system are essential.