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Advances in Radiotherapy
& Nuclear Medicine The novel index and osteoradionecrosis

the PIV-TE-ORNJ index. This novel three-tiered index TEs and those who had single or multiple TEs. However,
29
effectively categorized patients into three distinct ORNJ this patient selection process was conducted intentionally
risk groups: high risk (43.8%), intermediate risk (6.4%), to examine the effect of TE-related jaw trauma severity on
and low risk (1.1%). In addition, although a 6.4% incidence the incidence rates of ORNJ. Specifically, we analyzed the
of ORNJ in the intermediate-risk group was consistent with correlation between the number of teeth extracted and
the literature, 7-10 the 43.8% ORNJ incidence observed in the ORNJ occurrence rather than exclusively focusing on the
high-risk group was significantly higher than that in any presence or absence of TE. All participants in this study
other research. This finding indicates that nearly one out of exhibited poor oral health before C-CRT; therefore, the
every two patients in the high-risk group will experience generalization of our results to all patients with LA-NPC is
ORNJ at some point during post-C-CRT follow-up, not feasible. However, given the nearly identical oral health
emphasizing the importance of close dentistry follow-up conditions shared by nearly all participants, any associated
visits, early commencement of prophylactic measures, bias will likely be minimal, if present at all. Considering all
adoption of non-traumatic or minimally traumatic dental these facts together, the current findings are hypothesis-
extraction techniques, use of primary tissue closure after generating rather than concrete guidance until more
TEs, and more careful RT planning in the high-risk groups extensive prospective research can corroborate them.
to keep organ-at-risk doses as low as possible. 43,44 This study
also highlighted that the number of TEs serves as a more 6. Conclusion
crucial indicator of the severity of mandibular trauma The findings of this retrospective study involving patients
concerning ORNJ rather than the timing of TEs relative to with LA-NPC suggest that the newly developed PIV-TE-
the head and neck irradiation (pre- versus post-RT). This ORNJ index could effectively categorize patients into three
study revealed that the TE cutoff associated with increased distinct ORNJ risk groups following C-CRT, offering a
ORNJ risk was ≥4, a finding consistent with the cutoff of promising future for oncology practice. However, given the
>5 established by Tsai et al., that is, a 2.4% risk of ORNJ in study’s retrospective design and its limitation to a single
45
patients who underwent ≤5 TEs following RT, whereas the center, further studies are needed to confirm these results
risk increased to 12.1% in those who underwent >5 TEs before they can be incorporated into routine radiation and
(Z-score = 4.5062; P < 0.0001). dental oncology practice.

5. Limitations Acknowledgments
This study has several limitations. First, the findings None.
presented herein are based on a single institutional
retrospective study with a modest cohort size, and they lack Funding
associated internal and external validation cohorts. Second, None.
because the PIV is a dynamic biomarker with significant
time-dependent fluctuations, the fittest cutoff may differ Conflict of interest
from the one presented here, which merely reflected
single time-point measurements across all patients. Future The authors declare that they have no competing interests.
studies into the PIV obtained during or after C-CRT may Author contributions
be valuable in identifying a more relevant PIV cutoff
that may demonstrate a more reliable link with ORNJ Conceptualization: All authors
rates. Third, the lack of in vivo oxygen measurements or Formal analysis: All authors
vascular abnormalities necessitates considering blood flow Investigation: All authors
measurements and evaluating the tissue oxygenation status Methodology: All authors
in the treatment area before, during, and after C-CRT. This Writing–original draft: All authors
approach may prove valuable in identifying patients at a Writing–review & editing: All authors
high risk of developing ORNJ. Fourth, in the absence of Ethics approval and consent to participate
correlative analyses, we may have skipped the opportunity
to clarify the potential links between ORNJ occurrence and Baskent University Medical Faculty’s Institutional
levels of inflammatory biomarkers, such as HIF-1, VGEF, Review Board (IRB No. DKA 19/39) approved the
TNF-α, IL-1, IL-6, and TGF-β, which play critical roles retrospective investigation before collecting patient data.
in fibrosis formation and hypoxia and thus ORNJ. Fifth, This investigation was carried out in accordance with
because the study group had TEs before treatment, we were the principles outlined in the Helsinki Declaration and
unable to compare the results between patients who had no its later amendments. Before the C-CRT commenced,

Volume 3 Issue 1 (2025) 53 doi: 10.36922/arnm.5799