Jonathan Robert Clark

Prof. Dr. Jonathan Robert Clark

1. Sydney Medical School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
+2
orcid

Research Focus & Metrics

Academic Career Length

28Years (1999-Present)

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

Representative Publications

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11 June 2007 in Head & Neck
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JCJonathan Robert Clark
Jonathan Robert Clark
SMStuart A. McCluskey
Stuart A. McCluskey
FHFrancis Hall
Francis Hall
JLJoan Lipa
Joan Lipa
PNPeter Neligan
Peter Neligan
RGRalph Gilbert
Ralph Gilbert

24 September 2013 in British Journal of Cancer
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Journal Article
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SPS G Patel
S G Patel
MAM Amit
M Amit
TYT C Yen
T C Yen
CLC T Liao
C T Liao
PCP Chaturvedi
P Chaturvedi
Ziv GilZiv Gil
Ziv Gil
Lymph node density (LND) has previously been reported to reliably predict recurrence risk and survival in oral cavity squamous cell carcinoma (OSCC). This multicenter international study was designed to validate the concept of LND in OSCC. The study included 4254 patients diagnosed as having OSCC. The median follow-up was 41 months. Five-year overall survival (OS), disease-specific survival (DSS), disease-free survival (DFS), locoregional control and distant metastasis rates were calculated using the Kaplan–Meier method. Lymph node density (number of positive lymph nodes/total number of excised lymph nodes) was subjected to multivariate analysis. The OS was 49% for patients with LND0.07 compared with 35% for patients with LND>0.07 (P0.07 (P<0.001). Lymph node density reliably stratified patients according to their risk of failure within the individual N subgroups (P=0.03). A modified TNM staging system based on LND ratio was consistently superior to the traditional system in estimating survival measures. This multi-institutional study validates the reliability and applicability of LND as a predictor of outcomes in OSCC. Lymph node density can potentially assist in identifying patients with poor outcomes and therefore for whom more aggressive adjuvant treatment is needed.

16 July 2007 in Head & Neck
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Journal Article
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JCJonathan Robert Clark
Jonathan Robert Clark
MVMartin Vesely
Martin Vesely
RGRalph Gilbert
Ralph Gilbert
Background.: Maxillary reconstruction continues to challenge in terms of optimal aesthetic and functional outcomes. The aim of this study was to describe the utility of the scapular angle osteomyogenous flap in a series of maxillectomy patients and to examine the donor site morbidity.Methods.: This is a retrospective series of 14 patients undergoing maxillectomy and either primary or secondary reconstruction. The scapular angle can be oriented vertically and horizontally. Aesthetic, functional, and operative morbidity is described. The Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire was used to examine shoulder and upper limb morbidity.Results.: Perioperative morbidity occurred in 4 patients. There were no free flap failures. Functional and aesthetic outcomes were acceptable with all patients having intelligible speech and none requiring nutritional supplementation. The DASH was completed by 12 of 14 patients. The mean and median DASH scores were 10.6 and 13, respectively. All patients gained full range of shoulder movement by 6 months after surgery.Conclusions.: The scapular angle flap is well suited for maxillary reconstruction and donor site morbidity is low. © 2007 Wiley Periodicals, Inc. Head Neck, 2008

20 September 2013 in Cancer
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MAMoran Amit
Moran Amit
TYTzu‐Chen Yen
Tzu‐Chen Yen
CLChun‐Ta Liao
Chun‐Ta Liao
PCPankaj Chaturvedi
Pankaj Chaturvedi
JAJai Prakash Agarwal
Jai Prakash Agarwal
TCThe International Consortium for Outcome Research (ICOR) in Head and Neck Cancer
The International Consortium for Outcome Research (ICOR) in Head and Neck Cancer
BACKGROUND: An association between the survival of patients with oral cavity squamous cell carcinoma (OCSCC) and advancements in diagnosis and therapy has not been established.METHODS: This was a retrospective, longitudinal, international, population‐based study of 2738 patients who underwent resection of OCSCC during 2 different decades. Characteristics of patients from 7 international cancer centers who received treatment between 1990 and 2000 (group A; n = 735) were compared with patients who received treatment between 2001 and 2011 (group B; n = 2003).RESULTS: Patients in group B had more advanced tumors and tended to develop distant metastases more frequently than patients in group A (P = .005). More group B patients underwent selective neck dissection and received adjuvant radiotherapy (P < .001). Outcome analysis revealed a significant improvement in 5‐year overall survival, from 59% for group A to 70% for group B (P < .001). There was also a significant improvement in disease‐specific survival associated with operations performed before and after 2000 (from 69% to 81%, respectively; P < .001). Surgery after 2000, negative margins, adjuvant treatment, and early stage disease were independent predictors of a better outcome in multivariate analysis. The decade of treatment was an independent prognostic factor for cancer‐specific mortality (hazard ratio, 0.42; 95% confidence interval, 0.3‐0.6).CONCLUSIONS: The survival rate of patients with OCSCC improved significantly during the past 2 decades despite older age, more advanced disease stage, and a higher rate of distant metastases. The current results suggest that the prognosis for patients with OCSCC has improved over time, presumably because of advances in imaging and therapy. Cancer 2013;119:4242–4248. © 2013 American Cancer Society.

18 January 2011 in Cancer
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AEArdalan Ebrahimi
Ardalan Ebrahimi
WZWan J. Zhang
Wan J. Zhang
KGKan Gao
Kan Gao
JCJonathan Robert Clark
Jonathan Robert Clark
BACKGROUND: Elective neck dissection (END) is commonly used as a staging and therapeutic procedure for oral squamous cell carcinoma (SCC) at high risk of nodal metastases. The authors aimed to determine whether the extent of lymphadenectomy, as defined by nodal yield, is a prognostic factor in this setting.METHODS: A retrospective database review identified 225 patients undergoing END with curative intent for oral SCC between 1987 and 2009. Nodal yield was studied as a categorical variable for association with overall, disease‐specific, and disease‐free survival in univariate and multivariate analyses.RESULTS: Nodal yield <18 was associated with 5‐year overall survival of 51% compared with 74% in those with nodal yield ≥18 (P = .009). Five‐year disease‐specific survival rates were 69% in those with <18 nodes and 87% in patients with ≥18 nodes (P = .022). Similar results were obtained for disease‐free survival, with 5‐year rates of 44% with <18 nodes versus 71% with ≥18 nodes (P = .043). After adjusting for the effect of age, nodal status, T stage, and adjuvant radiotherapy on multivariate analysis, nodal yield <18 was associated with reduced overall (hazard ratio [HR], 2.0; 95% confidence interval [CI], 1.1‐3.6; P = .020), disease‐specific (HR, 2.2; 95% CI, 1.1‐4.5; P = .043), and disease‐free survival (HR, 1.7; 95% CI, 1.1‐2.8; P = .040). In the pathologically lymph node‐negative subgroup (n = 148), similar results were obtained.CONCLUSIONS: Nodal yield is an independent prognostic factor in patients undergoing END for oral SCC. These results suggest that an adequate lymphadenectomy in this setting should include at least 18 nodes. Cancer 2011. © 2011 American Cancer Society.

22 March 2011 in Cancer
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AEArdalan Ebrahimi
Ardalan Ebrahimi
RMRajmohan Murali
Rajmohan Murali
KGKan Gao
Kan Gao
MEMichael S. Elliott
Michael S. Elliott
JCJonathan Robert Clark
Jonathan Robert Clark
BACKGROUND: A study was undertaken to determine whether bone invasion is an independent prognostic factor in oral squamous cell carcinoma (SCC) after taking into account the extent of bone invasion.METHODS: The study was a retrospective review of 498 patients with oral SCC undergoing surgery with curative intent, 102 of whom had pathologically proven bone invasion. Bone invasion was categorized as absent, cortical, or medullary and tested for association with disease control and survival.RESULTS: After adjusting for potential confounding factors in multivariate analysis, there was no association between cortical invasion and overall (P = .48) or disease‐specific survival (P = .63). In contrast, medullary invasion was an independent predictor of reduced overall (hazard ratio [HR], 1.9; 95% confidence interval [CI], 1.2‐3.1; P = .006) and disease‐specific survival (HR, 2.1; 95% CI, 1.2‐3.6; P = .01), and this appeared to result from an increased risk of distant metastatic failure (P = .037) rather than local (P = .51) or regional recurrence (P = .14). Within the subset of patients with medullary invasion, survival differed significantly according to tumor size (P = .029).CONCLUSIONS: Patients with oral SCC and bone invasion have widely variable outcomes depending on the depth of bone invasion and tumor size. The results suggest that the current American Joint Committee on Cancer staging system, which classifies all tumors invading through cortical bone as T4, has limited prognostic utility. The authors recommend a revision of the T staging system such that tumors are classified as T1 to T3 based on size and then upstaged by 1 T stage in the presence of medullary bone invasion. Cancer 2011. © 2011 American Cancer Society.