Israel Medical Association Journal

Background: Intrathoracic cancer can cause hyponatremia, but it is uncertain whether mild hyponatremia in the outpatient setting should be regarded as an early sign of intrathoracic cancer.

Objectives: To evaluate the risk of undiagnosed intrathoracic cancer in patients with new persistent mild hyponatremia.

Methods: We conducted a retrospective cohort study using the electronic health record database of a large healthcare organization. The hyponatremia group included patients with sodium concentration of 130–134 mmol/L twice, after a previous normal value and without previous history of cancer or diseases related to hyponatremia. A control group with normal sodium concentration was matched by sex, age, and year of testing. We measured specific intrathoracic cancer incidence during 3 years of follow-up after sodium concentration test date. A logistic regression was used to adjust for further clinical information including smoking history, symptoms, and medications.

Results: The study comprised 1539 participants with mild hyponatremia and 7624 matched controls. New intrathoracic cancer diagnosis was more common in the hyponatremia group during a 3-year follow-up; 1.49% in the hyponatremia group and 0.39% in the control group, crude odds ratio (OR) 3.84, 95% confidence interval (95%CI) 2.22–6.63. After adjustment, hyponatremia remained a significant risk factor for the diagnosis of intrathoracic cancer; adjusted OR 3.61, 95%CI 2.08–6.28.

Conclusions: New mild persistent hyponatremia might be a significant predictive marker to a yet undiagnosed intrathoracic cancer.

Background: Multiple primary malignancies are increasingly being detected among cancer patients. Objectives: To investigate the co-occurrence of primary bladder cancer and primary lung cancer, two established smoking-related neoplasms characteristically associated with increased risk of secondary cancers.

Methods: A retrospective search of the patient registry in our institution identified 25 patients (23 men and two women) who were diagnosed with both bladder cancer and lung cancer during the period 1990–2005. Medical records were reviewed and clinical and pathological data were extracted.

Results: In 21 patients (84%) bladder cancer was the first primary tumor and in 4 (16%) the second primary tumor. More than 90% of the patients had a history of smoking. Mean smoking exposure was 62.1 pack years (range 30–120). All bladder cancers were transitional cell carcinomas with the majority being superficial at presentation. Most lung cancers were of the non-small cell type. Second primary lung cancers were significantly more advanced at diagnosis. Overall, mean follow-up was 105.8 months (range 6–288). Seven patients (28%) were alive at the time of evaluation; 68% died of lung cancer, while none died of bladder cancer.

Conclusions: Second primary lung cancer may occur in patients with bladder carcinoma and vice versa. In view of the relatively frequent involvement of the genitourinary tract as a site of multiple primary tumors, urologists may have a key role in the detection of second primary tumors arising in the genitourinary tract, or second primary tumors that occur in patients with primary genitourinary tract malignancies.