We collected a total of 202 cases in this retrospective study, including 148 male and 54 female, with a mean age of 56.3 (median 56, range 25-89) years old. Of the 202 patients, 155 showed up in our department with primary OSCC, and the remaining 47 had recurrent lesions after surgical treatment in other medical institutions. The mean follow-up period was 13.62 (median 10, range 1 to 56) months. The clinical parameters of all 202 patients are shown in table 1.
Relationship between preoperative plasma DD, FIB, PLT level and clinicopathologic parameters
Of the 202 patients, preoperative FIB and PLT levels were closely related with each other (r=0.376, P=0.000), however, preoperative DD level and preoperative FIB and PLT levels were not significantly related (P=0.053 and 0.636, respectively).
Preoperative plasma DD, FIB，PLT level and clinicopathologic parameters including age, sex, tumor location, TNM staging, surgical treatment and duration are summarized in table 2. The mean preoperative DD level was 499.45μg/L, and refer to the manufacturer’s recommendation, plasma DD level of 500μg/L was set as cutoff value for normal and high DD values. The mean preoperative FIB and PLT level was 3.33 g/L and 259.5*10^9/L, and were set as cutoff value for low and high value of FIB and PLT respectively. In this study, we found that preoperative DD level in different sex or age group patients was not statistically different (P=0.187 and 0.062 respectively), however, in different site of tumor, different T stage, N stage, and clinical stage patients, preoperative DD level was significantly different (P=0.040, 0.000, 0.001 and 0000 respectively). However, when concerning preoperative FIB and PLT levels, we found different results, preoperative FIB level was different in sex and N stage category only (P=0.025 and 0.002 respectively), and preoperative PLT level was different in tumor site and clinical stage category only (P=0.048 and 0.040 respectively).
The means of DD, FIB and PLT in primary oral cancer patients were 424.96μg/L, 3.49 g/L and 249.11*10^9/L respectively, and in patients with recurrent tumor were 752.07μg/L, 3.82 g/L and 283.72*10^9/L respectively. The difference of DD and FIB level between primary and recurrent cancer was of statistical significance (P=0.018 and 0.038 respectively) (Figure 1).
Relationship between postoperative DD change and treatment related parameters
We retrospectively observed postoperative DD level in the first 3 days after surgery, and 96 patients with postoperative DD results. Postoperative DD level was found elevated in all the 96 patients in the very first day after surgery, and slowly goes down with time. The elevated level was correlated with preoperative DD level (r=0.284, P=0.005) as well as the surgical type (r=0.344, P=0.001), but not the time consuming of surgery (P=0.244) (Table 3).
Survival analysis of primary OSCC patients
According to NCCN guideline and patient desire, the 155 primary OSCC patients were prescribed to different surgical plant, including 1) excision of primary lesion (19.4%), 2) excision of primary lesion and neck dissection (25%), 3) excision of primary lesion and vascularized free flap transplantation (0.9%), 4) excision of primary lesion, neck dissection and vascularized free flap transplantation (51.9%), and 5) un-operated (2.8%). Of the 155 primary oral cancer patients, recurrence was diagnosed in 33 patients after surgical treatment in our department, rated 21.29%，and 26 of them died in follow-up time. The time from surgery to disease progression ranged from 1 to 34 months. Univariate analyses revealed that N stage (P=0.003) and preoperative DD level (P=0.033) were predictors of PFS. And in multivariate analysis, we demonstrated that pre-surgery plasma DD level was an independent prognostic factor in patients with primary OSCC (P=0.042) (Table 4, figure 2).
In our study, PFS was 78.7%. Patients with normal preoperative DD (＜500μg/L) had a significant better PFS than patients with high preoperative DD (≥500μg/L) (81.7% vs.74.2%, P=0.027) .
The data that support the findings of this study are available from the corresponding author upon reasonable request.