Researchers studied 150 people with oral squamous cell carcinoma (a type of mouth cancer) to see if vitamin D levels affected how serious their cancer was. They found that nearly half the patients had low vitamin D levels. People with low vitamin D were more likely to have cancer that had spread to lymph nodes, spread to distant parts of the body, and invaded nerves. This suggests vitamin D might be important for predicting how aggressive someone’s mouth cancer could be, though more research is needed to understand why and whether vitamin D treatment could help.

The Quick Take

  • What they studied: Whether people with mouth cancer who have low vitamin D levels experience more serious cancer compared to those with normal vitamin D levels
  • Who participated: 150 patients with oral squamous cell carcinoma (a specific type of mouth cancer), with an average age of 65 years, followed for two years after diagnosis
  • Key finding: About 47% of patients had low vitamin D. Those with low vitamin D were significantly more likely to have cancer that spread to lymph nodes and other parts of the body, and cancer that invaded nerves in the mouth
  • What it means for you: If you have mouth cancer, your doctor might want to check your vitamin D levels as part of understanding how serious your cancer might be. However, this study doesn’t yet prove that taking vitamin D supplements will help—more research is needed before making that recommendation

The Research Details

This was a retrospective cohort study, which means researchers looked back at medical records of 150 patients who already had mouth cancer. They measured vitamin D levels in the patients’ blood when they were first diagnosed and then tracked what happened to them over two years. They recorded information about how advanced the cancer was, whether it had spread to lymph nodes, whether it invaded nerves, and whether the cancer came back or spread to other parts of the body.

The researchers divided patients into two groups: those with normal vitamin D levels and those with low vitamin D levels. Then they compared how the cancer behaved differently between these two groups. They also looked at whether the season of the year affected vitamin D levels, since sunlight exposure changes with seasons.

This type of study is useful for finding patterns and associations between factors (like vitamin D levels) and disease outcomes (like cancer spread). By looking at real patient data over time, researchers can identify whether low vitamin D appears to be connected to more aggressive cancer. This information can help doctors identify which patients might need closer monitoring and can guide future research into whether vitamin D plays a role in cancer development or progression.

This study has several strengths: it followed patients for a full two years, it measured vitamin D at the time of diagnosis (not later), and it looked at multiple important cancer features. However, because it’s a retrospective study looking at past records, researchers couldn’t control for all factors that might affect results (like sun exposure, diet, or other health conditions). The study was also done in one location, so results might differ in other populations. The findings are interesting but not definitive proof that vitamin D causes cancer to be more aggressive.

What the Results Show

Nearly half of the 150 patients (70 people, or 46.7%) had low vitamin D levels at the time of their mouth cancer diagnosis. Patients with low vitamin D were significantly more likely to have cancer that had spread to nearby lymph nodes—this difference was very statistically significant (p < 0.01, meaning there’s less than a 1% chance this happened by random chance).

Patients with low vitamin D also showed higher rates of perineural invasion, which means the cancer had invaded the nerves in the mouth area (p = 0.02, meaning there’s about a 2% chance this happened randomly). Additionally, low vitamin D was associated with cancer that had spread to distant parts of the body (metastasis).

Interestingly, the researchers found that low vitamin D levels were also connected to where the cancer appeared in the mouth—certain common locations had higher rates of low vitamin D patients. However, seasonal changes (which normally affect vitamin D levels due to sun exposure) did not significantly impact vitamin D levels in this group, suggesting other factors beyond season were responsible for the low levels.

The study found that vitamin D deficiency was associated with more aggressive tumor behavior overall. The combination of lymph node involvement, nerve invasion, and distant spread suggests that low vitamin D patients had more advanced disease at diagnosis. These are all markers that doctors use to predict how serious a cancer case is and what the likely outcome might be.

This research builds on earlier findings showing that vitamin D deficiency is linked to worse outcomes in other cancers, particularly colorectal cancer and breast cancer. This study extends that observation to mouth cancer, suggesting that vitamin D deficiency might be a general risk factor for more aggressive cancers across different body sites. However, the exact reason why low vitamin D is connected to worse cancer outcomes remains unclear and needs further investigation.

This study has important limitations to consider. First, it only looked at 150 patients in one location, so results might not apply to all populations. Second, researchers couldn’t control for many factors that might affect both vitamin D levels and cancer severity, such as sun exposure, diet, smoking, alcohol use, or overall health. Third, the study couldn’t prove that low vitamin D causes more aggressive cancer—it only shows an association or connection. Fourth, because researchers looked at past medical records, they couldn’t ensure all patients were measured and followed up in exactly the same way. Finally, the study doesn’t tell us whether treating low vitamin D would improve cancer outcomes.

The Bottom Line

Based on this research, doctors might consider measuring vitamin D levels in mouth cancer patients as one factor in assessing how serious the cancer might be. However, this study does NOT yet support recommending vitamin D supplements as a cancer treatment. More research is needed before making that recommendation. If you have mouth cancer, discuss vitamin D testing with your oncologist as part of your overall care plan.

This research is most relevant to people diagnosed with oral squamous cell carcinoma and their doctors. It may also interest people with a family history of mouth cancer or those with risk factors like tobacco or alcohol use. However, this study doesn’t provide guidance for preventing mouth cancer or for people without cancer. People should not start taking high-dose vitamin D supplements based solely on this research.

This study tracked patients for two years after diagnosis. If vitamin D does play a role in cancer progression, changes would likely occur over months to years, not days or weeks. Any potential benefit from vitamin D treatment would need to be evaluated over a similar timeframe in future clinical trials.

Want to Apply This Research?

  • If you have mouth cancer and your doctor recommends vitamin D monitoring, track your serum vitamin D levels (measured in ng/mL or nmol/L) at regular intervals—typically every 3-6 months—and record the date and value in your health app alongside your cancer treatment timeline
  • Work with your healthcare team to establish appropriate vitamin D levels through safe sun exposure, dietary sources (fatty fish, fortified dairy, egg yolks), or supplementation if recommended. Log any vitamin D-related interventions and any changes in your cancer symptoms or treatment response
  • Create a long-term tracking system that correlates your vitamin D levels with cancer progression markers (like imaging results or tumor markers) that your doctor monitors. Share this data with your oncology team at each visit to help identify any patterns specific to your situation

This research describes an association between low vitamin D and more aggressive mouth cancer, but does not prove that vitamin D deficiency causes cancer or that vitamin D supplements will treat cancer. If you have been diagnosed with oral squamous cell carcinoma or any cancer, consult with your oncologist before making any changes to your vitamin D intake or cancer treatment plan. Do not use this information to self-diagnose or self-treat. This summary is for educational purposes only and should not replace professional medical advice from your healthcare provider.