Abstract
Background/Aim: This prospective multi-central randomized phase II trial evaluated the efficacy and safety of oral Vitamin B12 500 μg/day replacement compared with oral Vitamin B12 1,500 μg/day in patients with Vitamin B12 deficiency after total gastrectomy for gastric cancer. Patients and Methods: Patients were randomly assigned to receive oral Vitamin B12 500 μg/day or Vitamin B12 1,500 μg/day in a 1:1 ratio with a minimization method. The primary endpoint was the incidence of a normal serum Vitamin B12 level at three months after treatment. Results: From January 2018 to December 2021, 3 institutions collaborated with the present study, and 74 patients were registered from these 3 institutions. The study was prematurely closed due to poor accrual after reaching almost 50% of its goal. Among the 74 recruited patients, 36 were allocated to the Vitamin B12 500 μg/day arm and 38 to Vitamin B12 1,500 μg/day arm. The incidences of patients with a normal Vitamin B12 level at 3 months (serum Vitamin B12 level >200 pg/ml) were 91.7% (33/36) in the Vitamin B12 500 μg/day arm and 100% (38/38) in the Vitamin B12 1,500 μg/day arm (p=0.3587). The types of clinical symptoms with Vitamin B12 deficiency that improved with Vitamin B12 treatment and the degree of improvement were also similar. Conclusion: Although the primary endpoint of the present study was not met, it was found that oral Vitamin B12 500 μg/day replacement is as effective and safe as oral Vitamin B12 1,500 μg/day replacement for Vitamin B12 deficiency.
Gastric cancer is the third leading cause of cancer death in the world and the most common malignancy worldwide (1, 2). Gastrectomy with lymphadenectomy is required for curative treatment of gastric cancer. In addition, when the tumor is located in the proximal site or entire site, total gastrectomy is needed to achieve complete resection (3, 4).
Vitamin B12 deficiency is an inevitable and serious problem after total gastrectomy (5, 6). Vitamin B12 plays an important role in DNA synthesis and the neurologic function (7, 8). Therefore, long-term Vitamin B12 deficiency can cause weakness, tiredness, macrocytic anemia, and neurological symptoms (7, 8). Vitamin B12 deficiency has recently become an increasingly important issue as a result of the increased incidence of proximal gastric cancer and longer patient survival with improved treatment outcomes (9, 10). The absorption of Vitamin B12 cycle begins to bind the intrinsic factor. This Vitamin B12 and intrinsic factor complex subsequently aids in the absorption of Vitamin B12 in the terminal ileum (11). As a result of the loss of the intrinsic factor after total gastrectomy, the treatment for consequent Vitamin B12 deficiency has traditionally been intramuscular injections. Although the intramuscular injection of Vitamin B12 has been shown to be safe and feasible, the injections are painful and decrease patients’ quality of life.
Recently, oral Vitamin B12 treatment demonstrated an efficacy equal to intramuscular Vitamin B12 injections for Vitamin B12 deficiency after total gastrectomy (12, 13). In Korea, Kim et al. investigated the efficacy and safety of oral Vitamin B12 replacement (1,500 μg/day) for gastric cancer patients with Vitamin B12 deficiency after total gastrectomy (14). They found that oral Vitamin B12 replacement was as effective and safe as intramuscular Vitamin B12 injections for Vitamin B12 deficiency in this population. Another study demonstrated the efficacy and safety of oral Vitamin B12 replacement (500 μg/day) for gastric cancer patients with Vitamin B12 deficiency after total gastrectomy (15). Although some studies have shown the clinical effects of oral Vitamin B12 for B12 deficiency after total gastrectomy, there have been no prospective randomized trials evaluating oral Vitamin B12 treatment for B12 deficiency after total gastrectomy. In addition, the optimal dose of Vitamin B12 replacement for these patients is unclear.
Given the above, we hypothesized that oral Vitamin B12 500 μg/day replacement might have clinical efficacy on Vitamin B12 deficiency after total gastrectomy for gastric cancer. To confirm our hypothesis, this prospective randomized phase II trial was performed to compare the efficacy of oral Vitamin B12 500 μg/day replacement to that of oral Vitamin B12 1,500 μg/day in patients with Vitamin B12 deficiency after total gastrectomy for gastric cancer.
Patients and Methods
Study design. The present clinical trial was a randomized, open-label, multicenter, phase II study. The trial was performed in patients diagnosed with stage I to III gastric cancer. Patients were randomly assigned to receive oral Vitamin B12 500 μg/day or Vitamin B12 1,500 μg/day in a 1:1 ratio with a minimization method in order to balance treatment allocation according to the pathological stage (pathological stage I or pathological stage II/III) and medical center. The primary endpoint was the incidence of a normal serum Vitamin B12 level. The secondary endpoints were the improvement of neurologic symptoms and safety. This clinical trial was registered at the University Hospital Medical Information Network Clinical Trials Registry (UMIN000030727).
Ethics. Study data and informed consent were obtained in accordance with the Declaration of Helsinki and approved by the Ethics Review Board of each institution (B171207003). All patients were given a written explanation of the study, and they provided their written informed consent before participating.
Inclusion and exclusion criteria. Tumors were staged according to the 14th edition of the general rules for gastric cancer published by the Japanese Gastric Cancer Association (16). The inclusion criteria were as follows: 1) Stage I to III, histologically-proven gastric adenocarcinoma; 2) Patients who underwent curative total gastrectomy; 3) Vitamin B12 level <200 pg/ml with vitamin deficiency-related symptoms; 4) Adequate hematologic, liver, and coagulation profiles (white blood cell (WBC) count ≥3,000/mm3 and ≤12,000/mm3, neutrophil count ≥1,500/mm3, platelet count ≥100,000/mm3, glutamic oxaloacetic transaminase (GOT) ≤100 U/l and glutamic pyruvic transaminase (GPT) ≤100 U/l, total bilirubin <1.5 mg/dl, creatinine <1.5 mg/dl, and a normal electrocardiogram (ECG)); and 5) Provided their consent to participate in this clinical study. The exclusion criteria were as follows: 1) Presence of serious coexisting morbidities; 2) Active synchronous or metachronous malignant disease; 3) Pregnant or lactating; and 4) Deemed not suitable for participating in the study for any other reason.
Treatment methods
Oral Vitamin B12 500 μg/day arm: Methylcobalamin (Eisai Co., Ltd., Tokyo, Japan) was administered. The dosage comprised one 500-μg tablet of Methylcobalamin for a total of 500 μg daily.
Oral Vitamin B12 1,500 μg/day arm: Methylcobalamin was administered. The dosage comprised three 500-μg tablets of Methylcobalamin for a total of 1,500 μg daily.
Follow-up. Before the start of treatment and one, two, and three months after Vitamin B12 replacement, serum specimens including Vitamin B12 were obtained. A patient questionnaire that included 10 questions pertaining to clinical symptoms of Vitamin B12 deficiency was completed before and one, two, and three months later. These symptoms included feeling tired, dyspnea or dizziness, stomatitis, loss of appetite, palpitation, tingling sensations and/or paresthesia of hands or feet, tremor, memory impairment, and irritability (Table I). The same physician assessed the safety of Vitamin B12 administration before and every month after administration through laboratory tests and patient interviews.
Questionnaire used to assess the symptoms of vitamin B12 deficiency.
Statistical analyses. We assumed an incidence of a normal serum Vitamin B12 level of 95% in each treatment group. A sample size of 80 patients in each group was determined necessary to provide a statistical power of 0.8 to show non-inferiority of Vitamin B12 500 μg/day to 1,500 μg/day for the incidence using the binomial test with a non-inferiority margin of 10% and a 1-sided significance level of 0.025. Efficacy analyses were performed in the full analysis set, which included all participants who received oral Vitamin B12 and grouped according to their treatment assignment. Safety analyses were performed in the safety analysis set, which included all participants who received oral Vitamin B12. The binomial test was employed to detect the non-inferiority of the incidences of a normal serum Vitamin B12 level. The incidence was estimated with the binomial proportion and Clopper-Pearson 95% confidence interval. Wilcoxon’s signed-rank test and Wilcoxon’s rank sum test were used to compare the distributions of the questionnaire score within and between groups, respectively. All statistical analyses were performed using the R software program, version 4.1.0 (R Foundation for Statistical Computing, Vienna, Austria).
Results
Recruitment and patients’ characteristics. From January 2018 to December 2021, 3 institutions collaborated with the present study, and 74 patients were registered from these 3 institutions. The study was prematurely closed due to poor accrual after reaching almost 50% of its goal. The primary endpoint of the present study was unmet, and the power for the formal statistical analysis was limited.
Of the 74 patients, 36 were allocated to the Vitamin B12 500 μg/day arm and 38 to the Vitamin B12 1,500 μg/day arm. Figure 1 shows the consort diagram of the present study. Primary analyses were based on data from all randomly assigned patients. The two groups were well balanced with regard to the baseline clinical characteristics and pathological findings (Table II).
Consort diagram of the present study.
Comparison patient’s background between the Vitamin B12 500 μg and Vitamin B12 1,500 μg groups.
Safety and feasibility. Table III shows the adverse events reported in the present study. The reported adverse events of grade ≥2 in the Vitamin B12 500 μg/day arm were ileus (grade 2) and anemia (grade 2), while there were no adverse events of grade ≥2 in the Vitamin B12 1,500 μg/day arm. No adverse events of grade 3 or 4 were observed.
Relevant adverse events.
Among the 36 patients in the efficacy population who received Vitamin B12 500 μg/day, the relative dose intensity (RDI) at 3 months after treatment of Vitamin B12 500 μg/day was >70% in 33 patients (91.7%), 50%-70% in 2 patients (5.6%), and <50% in 1 patient (2.7%). The RDI of Vitamin B12 1,500 μg/day was >70% in 37 patients (97.4%), 50%-70% in 1 patient (2.6%), and <50% in 0 patient (0%).
Laboratory results. Table IV shows the details of laboratory results between the Vitamin B12 500 μg/day arm and Vitamin B12 1,500 μg/day arm. In all patients, serum Vitamin B12 levels increased after the administration of Vitamin B12 in both arms (Figure 2). The median level of Vitamin B12 was 230 pg/ml at 1 month, 323 pg/ml at 2 months, and 301 pg/ml at 3 months in the Vitamin B12 500 μg/day arm, and the median level of Vitamin B12 was 352 pg/ml at 1 month, 426 pg/ml at 2 months, and 410 pg/ml at 3 months in the Vitamin B12 1,500 μg/day arm. The incidences of a Vitamin B12 normal level at 3 months (serum Vitamin B12 level >200 pg/ml) were 91.7% (33/36; 95%CI=77.5-98.2%) in the Vitamin B12 500 μg/day arm and 100% (38/38; 95%CI=90.7-100%) in the Vitamin B12 1,500 μg/day arm (Non-inferiority, p=0.3587).
Comparison laboratory results before and after between the Vitamin B12 500 μg and Vitamin B12 1,500 μg group.
Serum Vitamin B12 levels before and after treatment in the Vitamin B12 500 μg/day arm and Vitamin B12 1,500 μg/day arm.
Questionnaire results. A questionnaire analysis was performed to compare the Vitamin B12 500 μg/day arm and Vitamin B12 1,500 μg/day arm. All of the patients had at least one symptom listed in the questionnaire at the beginning of the study. The most frequent clinical symptom was easily tired, followed by memory problems and easily irritated in the oral Vitamin B12 arm, while the most frequent clinical symptom was easily tired, followed by memory problems and tingling sensations in the hands or feet in the oral Vitamin B12 arm (Figure 3). Similar improvement trends (number before treatment to number after treatment) were observed in the Vitamin B12 500 μg/day arm and Vitamin B12 1,500 μg/day arm. The proportions of easily tired improved to 30.5% (23 to 16) and 28.6% (28 to 20), the proportions of memory problems improved to 50.0% (20 to 10) and 35.0% (20 to 13), the proportions of tingling sensation in the hands or feet improved to 40.0% (10 to 6) and 43.8% (16 to 9), and the proportions of easily irritated improved to 61.5% (13 to 5) and 41.7% (12 to 7), respectively. The rate of improvement in clinical symptoms was not significantly different between the Vitamin B12 500 μg/day arm and Vitamin B12 1,500 μg/day arm (Figure 4). In the Vitamin B12 500 μg/day arm, the median number of grade ≥2 clinical symptoms was 3 before treatment and 1 after treatment. In the Vitamin B12 1,500 μg/day arm, the median number of grade ≥2 clinical symptoms was 3 before treatment and 1 after treatment.
Details of clinical symptoms before and after treatment in the Vitamin B12 500 μg/day arm and Vitamin B12 1,500 μg/day arm.
Number of clinical symptoms before and after treatment in the Vitamin B12 500 μg/day arm and Vitamin B12 1,500 μg/day arm.
Discussion
The present randomized phase II study aimed to confirm our hypothesis that oral Vitamin B12 500 μg/day replacement has equal clinical efficacy to oral Vitamin B12 1,500 μg/day replacement for patients with Vitamin B12 deficiency after total gastrectomy for gastric cancer. Although the primary endpoint of the present study was unmet and the failure to reach the target sample size in the present trial indicated that the target statistical power could not be guaranteed, the major findings were that oral Vitamin B12 500 μg/day replacement was indeed as effective and safe a treatment as oral Vitamin B12 1,500 μg/day replacement for Vitamin B12 deficiency. These results suggest that oral Vitamin B12 500 μg/day replacement might be a viable treatment option for Vitamin B12 deficiency after total gastrectomy for gastric cancer.
First, we want to discuss the serum Vitamin B12 level in the oral Vitamin B12 500 μg/day arm compared to the Vitamin B12 1,500 μg/day arm. In the present study, we did not prove our hypothesis due to the poor patient accrual. However, the incidences of patients with a normal Vitamin B12 normal level at 3 months after treatment were similar between the oral Vitamin B12 500 μg/day arm and oral Vitamin B12 1,500 μg/day arm (91.7% vs. 100%, p=0.3587). In addition, the subgroup analysis showed that both oral Vitamin B12 500 μg/day and oral Vitamin B12 1500 μg/day had similar effects on the serum Vitamin B12 level, regardless of the age, sex, pathological stage, and Vitamin B12 status before treatment. However, there were three patients who did not have a normal Vitamin B12 level at 3 months after treatment in the oral Vitamin B12 500 μg/day arm, possibly because of a low compliance with oral Vitamin B12 in the oral Vitamin B12 500 μg/day arm. The details concerning the compliance with oral Vitamin B12 500 μg/day in these 3 patients were as follows: 2 patients had 50%-70% compliance, and 1 had <50% compliance. However, all patients with >70% compliance had a normal Vitamin B12 level at 3 months after treatment in the oral Vitamin B12 1,500 μg/day arm. The continuation rate of Vitamin B12 might affect the Vitamin B12 level at three months after treatment.
Second, we want to discuss the improvement in the clinical symptoms associated with Vitamin B12 deficiency. When comparing the clinical symptoms due to Vitamin B12 deficiency between two groups, we noted similar clinical effects and improvements. Easily getting tired was the most prevalent symptom in the whole cohort, affecting 51 out of 74 patients (68.9%), followed by memory problems (40/74, 54.1%) and easily being irritated (25/74, 33.8%). These symptoms were resolved by three months later in both treatment arms. Almost 30% of patients who felt tired had their symptom relieved after treatment in both arms. In addition, almost half of patients with memory problems and who were easily irritated had their symptoms relieved after treatment in both arms. The frequency and types of clinical symptoms with Vitamin B12 deficiency before treatment were similar between the two groups, and the types of clinical symptoms associated with Vitamin B12 deficiency that improved with treatment and the degree of improvement were also similar. In addition, the improvement in the number of clinical symptoms was also similar. Therefore, oral vitamin treatment might be effective for treating clinical symptoms due to Vitamin B12 deficiency regardless of the dose of Vitamin B12 treatment. Given these two major findings of improvement in the serum Vitamin B12 level and the clinical symptoms due to Vitamin B12 deficiency, although the present study had a low statistical power, oral Vitamin B12 500 μg/day replacement might be a viable treatment option for Vitamin B12 deficiency after total gastrectomy for gastric cancer.
The present study included two cases of adverse events in the oral Vitamin B12 500 μg/day arm, with details as follows: 1 case of anemia due to iron deficiency and 1 case of ileus following total gastrectomy. Thus, there was no relationship between the adverse events and oral Vitamin B12 treatment. There were also no adverse events at all in the oral Vitamin B12 1,500 μg/day arm. Continuation rates exceeding 70% for oral Vitamin B12 at 3 months were 92% in the oral Vitamin B12 arm 500 μg/day and 100% in the oral Vitamin B12 arm 1,500 μg/day. Therefore, oral Vitamin B12 treatment was deemed safe and feasible for patients who received total gastrectomy for gastric cancer.
In conclusion, although the failure to reach the target sample size in the present trial indicated that the primary endpoint was not met, oral Vitamin B12 500 μg/day replacement might be a viable treatment option for Vitamin B12 deficiency after total gastrectomy for gastric cancer.
Acknowledgements
This work was supported by JSPS KAKENHI Grant Number 21K08688. The Authors express their sincere gratitude to Ms. Akiko Yoshida, Ms. Emiko Saito, Ms. Yuka Maruyama, Ms. Minako Igarashi and Ms. Mariko Yamauchi for their excellent data management in this study.
Footnotes
↵* These Authors contributed equally to this study.
Authors’ Contributions
TA, YM, and YR made substantial contributions to the concept and design. TA, HC, KT, KK, AT, KK2(Kazuki Kano), KH, HT, TO, NYYS, JT, KS, YS, MY, and YR made substantial contributions to the acquisition of data and the analysis and interpretation of the data. TA, HT, TO, NY, and YR were involved in drafting the article or revising it critically for important intellectual content. TA, YM, KK, and TO give their final approval of the version to be published.
Conflicts of Interest
The Authors declare no conflicts of interest in association with the present study.
- Received June 10, 2022.
- Revision received June 23, 2022.
- Accepted June 24, 2022.
- Copyright © 2022 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.
