Patients with advanced cancer present various symptoms as their disease progresses. Among these, fatigue is a frequent symptom in patients with advanced cancer and is associated with decreased quality of life (QOL). However, there are few reports regarding its association with thiamine deficiency (TD).

We report a case in which we found TD in a patient with advanced lung cancer who presented with weight loss, significant fatigue, and appeared to have a worsening general condition, for whom symptoms were dramatically improved within a short period of time by intravenous administration of thiamine.

The patient was a 76-year-old woman who had been diagnosed with lung cancer and liver metastases 6 months earlier. Due to interstitial pneumonia, she was not a candidate for chemotherapy and so palliative care was started. At 8 months after initial diagnosis, the patient complained of fatigue during a medical examination, so a blood sample was taken. A week later, she visited the hospital with a cane. She felt extremely fatigued and was unable to stand, but results from the previous blood test revealed that a TD. The fatigue disappeared 15 minutes after intravenous administration of thiamine and she was able to return home without the cane.

Fatigue is a frequent symptom in advanced cancer patients, and TD may be the underlying cause. Inclusion of TD in the differential diagnosis may contribute to improving patient QOL.

Thiamine deficiency (TD) presents with various physical and psychiatric symptoms, but no cases with depression-like symptoms have been reported.

We report a patient with cancer who appeared to attempt suicide as a consequence of depressive mood likely related to TD.

The patient was a 58-year-old woman diagnosed with recurrent endometrial cancer, with lung metastasis and pelvic dissemination. The patient apparently attempted suicide was referred to the psycho-oncology department.

At the time of the examination, major depressive disorder was suspected based on her mental symptoms, but when thiamine was administered intravenously in response to her poor dietary intake, her palpitations, dyspnea, anorexia, and insomnia improved, and her suicidal ideation disappeared at her reexamination 1 hour later after thiamine administration.

It is likely that the observed palpitations, dyspnea, anorexia, and insomnia, as well as the severe depression and the attempted suicide, which were thought to be physical symptoms associated with depression, were actually related to TD. Suicidal ideation and attempted suicide are conspicuous as psychiatric symptoms. However, in such cases, rather than simply starting treatment for depression, it is necessary to consider reversible TD as a cause of these symptoms and perform differential diagnosis to confirm the physical illness.

Despite increasing reports of thiamine deficiency (TD) among cancer patients, there remain some patients with borderline thiamine concentrations (BTC). However, it is unclear whether such patients subsequently develop TD.

Here, we report cases of cancer patients progressing to TD within a short time period after presentation with BTC (24–28 ng/ml).

A 49-year-old female with lung cancer. During treatment for depression, the patient showed a decreased appetite, and a blood sample revealed BTC (25 ng/ml). Fourteen days later, she reported a continued loss of appetite, and despite the absence of the 3 classical signs of Wernicke encephalopathy (WE), additional testing showed a thiamine level of 23 ng/ml, leading to a diagnosis of TD.

A 65-year-old female developed depression during chemotherapy for angiosarcoma. Her blood sample revealed BTC (25 ng/ml). Seven days later, despite the absence of the classical signs of WE, a further testing revealed a thiamine level of 20 ng/ml.

A 41-year-old female developed depression during chemotherapy for ovarian cancer. No loss of appetite was observed, but a blood sample revealed BTC (25 ng/ml). Seven days later, despite the absence of the classical signs of WE or decreased appetite, further testing revealed a thiamine level of 19 ng/ml.

Depressed cancer patients with BTC may develop TD within a short time frame. To prevent TD, health-care professionals should maintain an awareness of its potential and the need for regular testing of thiamine level or prophylactic replacement therapy.

It is well known that the burden on the families of cancer patient extends across many aspects, but there have been no reports of family members developing delirium due to the burden of caring for a cancer patient.

We reported a caregiver who developed Wernicke encephalopathy (WE) while caring for a family member with advanced cancer.

The subject was a 71-year-old woman who had been caring for her husband, diagnosed with gastric cancer and liver metastases, for 5 months. She visited the “caregivers’ clinic” after referral by an oncologist who was worried about a deterioration in her mental condition that had appeared several weeks previously. The woman had a history of diabetes mellitus. Some giddiness was observed and, based on her inability to answer questions, her level of consciousness was checked and some disorientation was observed. She was diagnosed with delirium. A blood sample was collected to investigate the cause of the delirium, but the test data showed no hypoglycemia. Her appetite had declined since her husband was diagnosed with cancer. Thiamine deficiency was suspected as thiamine stores in the body are depleted within about 18 days and her loss of appetite had continued for 5 months. On intravenous injection of 100 mg of thiamine, her consciousness level was returned to normal in 1 h. A diagnosis of WE was supported by the patient's abnormally low serum thiamine level.

The family members of cancer patients may develop a loss of appetite due to the burden of caring, resulting in WE. When providing care for signs of distress in family members, it is necessary to pay attention not only to the psychological aspects but also to their level of consciousness and physical aspects, particularly the possibility of serious illness resulting from reduced nutritional status.

Cancer patients often want to spend their final days at home, and it is essential that general practitioners have knowledge of and technical skills related to cancer medicine and symptom relief. Recent clinical studies have revealed that Wernicke encephalopathy (WE) is quite common in cancer patients. However, there have been no reports to date on WE in cancer patients undergoing home medical care.

From a series of cancer patient undergoing home medical care, we reported a patient with lung cancer who developed WE.

An 84-year-old female with lung cancer undergoing home medical care developed an impaired mental state and an attention deficit. Her symptoms fulfilled the diagnostic criteria for delirium. WE was suspected as the patient's food intake had fallen from normal a month previously to somewhere between 50% or just a few mouthfuls. This diagnosis was supported by abnormal serum thiamine and the disappearance of delirium after thiamine administration.

When delirium occurs in cancer patients undergoing home treatment, it is necessary to suspect thiamine deficiency as a potential cause, as appropriate diagnosis and treatment can prevent irreversible brain-related sequelae.

The symptoms of thiamine deficiency vary considerably and asymptomatic cases; i.e., subclinical thiamine deficiency (SCTD), are known to exist. However, there is no information available on the treatment of SCTD.

We report a patient who underwent intravenous thiamine replacement therapy for about a month after being diagnosed with SCTD, but who developed SCTD again about three weeks after finishing the treatment.

The patient was a 64-year-old woman who, after starting treatment for cervical cancer, complained of anxiety and underwent an initial psychiatric examination. The psychiatric diagnosis was an adjustment disorder. Based on the possibility of SCTD complications due to her decreased appetite and weight loss, her serum thiamine concentration was measured and found to be low. Therefore, thiamine was administered intravenously for 29 days. At the end of treatment, thiamine administration was discontinued as there were no apparent neuropsychiatric symptoms or problems with appetite. Twenty-three days later, there were still no problems with appetite or neuropsychiatric symptoms, but a follow-up blood sample revealed that her serum thiamine was again below the normal range.

Currently, there is no information available regarding the diagnosis and treatment of SCTD in cancer patients. In some cases, such as this case, the deficiency recurs without any symptoms indicative of SCTD; therefore, further examination for diagnosis and treatment is necessary.

Nivolumab has become an effective treatment option for cancer in various sites; however, this drug may cause immune-related adverse effects due to its mechanism of action. Furthermore, little has been reported on thiamine deficiency (TD) in patients receiving nivolumab treatment.

From a series of cancer patients, we reported a patient with recurrent renal cell carcinoma who developed TD after the start of nivolumab treatment.

A 74-year-old man with recurrent renal cell carcinoma was referred to the psycho-oncology department as he had lost about 4 kg and displayed a loss of energy after four cycles of nivolumab treatment. Psychiatric interviews revealed a decrease in energy. Neurological examination did not reveal any impairment in consciousness, ataxia, or ocular symptoms. He did not develop appetite loss. The malabsorption or overconsumption of some nutrients is thought to occur due to the rapid loss of weight; thus, a reduction in vitamin B1, which has a short storage period in the body and is often deficient in cancer patients, was suspected. The diagnosis of TD was supported by the patient's abnormally low serum thiamine level.

In patients treated with nivolumab, it is necessary to pay careful attention to TD when proceeding with the treatment. It is hoped that future research may reveal the link between nivolumab administration and TD.

Thiamine deficiency (TD) is recognized in various kinds of disease with associated loss of appetite including cancer; however, TD has not been recognized in the family caregivers of cancer patients to date.

From a series of cancer patient caregivers, we reported an aged family caregiver who developed TD while caring for the cancer patient.

The caregiver was a 90-year-old male. He had been accompanying his wife, who was diagnosed with colon cancer 4 years previously, on hospital visits as the primary caregiver, but because of psychological issues, he was recommended to visit the psycho-oncology department's “caregiver's clinic” for a consultation. Detailed examination revealed that his appetite had been only about 50% of usual from about one year before, and he had lost 12 kg in weight in one year. The diagnosis of TD was supported by his abnormally low serum thiamine level.

This report demonstrates that there is a possibility that care providers could develop TD from the burdens associated with caregiving. TD should be considered whenever there is a loss of appetite lasting for more than 2 weeks, and medical staff should pay careful attention to the physical condition of care providers to prevent complications resulting from TD.

Although thiamine deficiency (TD) and Wernicke encephalopathy (WE) are not rare in cancer patients, the cases reported to date developed TD and/or WE after treatment had started.

From a series of cancer patients, we report a patient diagnosed with TD without the typical clinical symptoms of WE at the preoperative psychiatric examination.

A 43-year-old woman with ovarian cancer was referred by her oncologist to the psycho-oncology outpatient clinic for preoperative psychiatric evaluation. Her tumor had been growing rapidly before the referral. Although she did not develop delirium, cerebellar signs, or eye symptoms, we suspected she might have developed TD because of her 2-month loss of appetite as the storage capacity of thiamine in the body is approximately 18 days. The diagnosis of TD was supported by abnormally low serum thiamine levels.

Cancer therapists need to be aware that thiamine deficiency may occur even before the start of cancer treatment. In cases with a loss of appetite of more than 2 weeks’ duration, in particular, thiamine deficiency should be considered if the tumor is rapidly increasing, regardless of the presence or absence of delirium.

Wernicke encephalopathy (WE) is a neuropsychiatric disorder caused by thiamine deficiency. It is recognized in various stages of the cancer trajectory but has not previously been recognized during nivolumab treatment.

From a series of WE patients with cancer, we report a lung cancer patient who developed WE during treatment with nivolumab.

A 78-year-old woman with lung cancer was referred to our psycho-oncology clinic because of depressed mood. Psychiatric examination revealed disorientation to time, date, and place, which had not been recognized 1 month previously. Her symptoms fulfilled the diagnostic criteria for delirium. No laboratory findings or drugs explaining her delirium were identified. WE was suspected as she experienced a loss of appetite lasting 4 weeks. This diagnosis was supported by abnormal serum thiamine and the disappearance of delirium after intravenous thiamine administration.

We found WE in an advanced lung cancer patient receiving treatment with nivolumab. Further study revealed the association between nivolumab and thiamine deficiency. Oncologists should consider thiamine deficiency when a patient experiences a loss of appetite of more than 2 weeks regardless of the presence or absence of delirium.

Wernicke encephalopathy (WE) is a neuropsychiatric disorder caused by thiamine deficiency, and is sometimes overlooked because of the diversity of clinical symptoms.

From a series of WE patients with cancer, we report a lung cancer patient who developed WE, the main symptom of which was agitation.

A 50-year-old woman with lung cancer was referred to our psycho-oncology clinic because of agitation lasting for three days. No laboratory findings or drugs explaining her agitation were identified. Although the patient did not develop delirium, ophthalmoplegia, or ataxia, WE was suspected because she experienced a loss of appetite loss lasting 5 weeks. This diagnosis was supported by abnormal serum thiamine and disappearance of agitation one hour after intravenous thiamine administration.

This report emphasizes the clinical diversity of WE and indicates the limits of the ability to diagnose WE from typical clinical symptoms. The presence of a loss of appetite for more than two weeks may be the key to the accurate diagnosis of WE.

Wernicke encephalopathy (WE) is a neuropsychiatric disorder caused by thiamine deficiency. Several reports of WE in cancer patients are known. WE is sometimes overlooked because most patients do not exhibit its typical symptoms (e.g., delirium, ataxia, ocular palsy). If delirium is not present, a diagnosis of WE is difficult because delirium is the hallmark symptom of WE.

Taken from a series on WE in cancer, we report two patients who developed WE without delirium during periodic psycho-oncology outpatient visits.

Case 1. A 61-year-old woman with non-Hodgkin lymphoma who was periodically attending a psycho-oncology outpatient clinic developed an unsteady gait. WE was suspected because she also developed appetite loss for two weeks, and we could find no other laboratory findings to explain her unsteady gait. Our diagnosis was supported by abnormal serum thiamine and disappearance of the gait disturbance after intravenous thiamine administration. Case 2. A 50-year-old woman with breast carcinoma with bone metastasis developed an unsteady gait. WE was suspected because she also developed loss of appetite for two weeks, and no other laboratory findings could explain her unsteady gait. The diagnosis was supported by abnormal serum thiamine and disappearance of the gait disturbance after administration of intravenous thiamine.

Our report emphasizes the importance of being aware of WE, even when patients do not present with delirium. The presence of loss of appetite for more than two weeks may be the key to a diagnosis of WE.

Few reports of Wernicke encephalopathy in oncological settings have been published. Some cases of Wernicke encephalopathy are related to appetite loss; however, the degree to which loss of appetite leads to thiamine deficiency is not known.

A 63-year-old female with advanced cancer of the external genitalia was referred for psychiatric consultation because of disorientation, insomnia, and bizarre behaviors. Her symptoms fulfilled the diagnostic criteria for delirium. Routine laboratory examinations did not reveal the cause of the delirium. Thiamine deficiency was suspected because appetite loss had continued for 19 days since she had been admitted to hospital.

Intravenous administration of thiamine resulted in recovery from the delirium within three days. Serum thiamine level was found to be 16 ng/ml (normal range: 24–66 ng/ml). The clinical findings, the low level of thiamine in the serum, and the effective alleviation of delirious symptoms after thiamine administration fulfilled Francis's criteria for delirium induced by thiamine deficiency.

Clinicians must be aware of the possibility of Wernicke encephalopathy in cancer patients, especially in those with loss of appetite for longer than 18 days. The degree of appetite loss in such patients might serve as a reference. Early detection and intervention may alleviate the symptoms of delirium and prevent irreversible brain damage.