Our study showed a significant decrease in NDLC cases in 2020 compared to the previous three years, especially during the COVID-19 pandemic onset and stay-at-home restriction period.
Early diagnosis of lung cancer and an early stage are factors that increase survival by increasing the chance of surgery. While the 5-year survival rate is 50% in Stage 1A lung cancer, this rate drops to 2% in Stage 4 . Only less than 20% of patients present at the operable stages . There are patient or system-related reasons for patients' late admission to the hospital. Patient-related causes include age, gender, socioeconomic status, employment status, and awareness of smoking. Patients with chronic illnesses might apply late due to their chronic symptoms or health condition. The reasons originating from the physicians or the health system might be summarized as follows: examination by a physician from other than chest diseases, misinterpretation of radiology, focusing on different diagnoses, not getting an appointment due to systemic problems, or late diagnostic procedures .
Epidemics such as COVID-19 affect the entire health system, affecting patients' hospital admission and receiving adequate health care. Several studies show a decrease in the number of cranial imaging performed to detect stroke or hospitalization due to acute myocardial infarction during the COVID-19 pandemic [11, 12]. Cancer patients may also be affected by this situation, and diagnosis may be delayed due to late hospital admission. It has been shown that there is a 25% reduction in cancer cases in the March-May 2020 pandemic period in the Netherlands . In Spain, between March and June 2020, the number of new cancer cases decreased by 20.8% compared to 2019, the number of biopsies performed for diagnosis was lower, and the number of visits for patients receiving cancer treatment decreased . In a study from the USA, the number of cases of six cancer types, including lung cancer, decreased significantly in March and April compared to the first two months of 2020 . In our study, there was a significant decrease in hospital admissions in NDLC cases, especially during the lockdown periods of the pandemic. According to GCO 2020, the total number of lung cancer cases detected in Turkey was not lower than in 2018. However, the number of NDLC cases diagnosed in our hospital in 2020 was lower than in previous years. This difference might be due to the GCO registry system using other nine cities’ hospital data of the country except our tertiary chest diseases hospital. The other factors contributing to the low number of NDLC cases may be as follows; caring for active COVID -19 patients in our hospital, can not performing interventional procedures in the first period of the pandemic, and then performing less in number than previous years during the entire pandemic period.
A published meta-analysis observed that a 12-week delay in surgery in lung cancer patients significantly reduced survival . In Park et al.'s study, during the COVID-19 pandemic in Korea, NSCLC patients applied at a more advanced stage than in previous years . Although the stages of the patients and the treatments they received could not be documented in our study, the decrease in the admissions of NDLC patients, especially during the restriction periods of the pandemic, may cause to apply in the advanced stages and reduce the survival. A modeling study from England showed that there might be a 4.8-5.3% higher mortality within five years in lung cancer patients due to delayed diagnosis in the COVID-19 period .
It should also be kept in mind that lung cancer patients have a higher risk of contracting COVID-19, and mortality may be higher due to infection. It has been reported that 76% of patients with thoracic malignancies infected with COVID-19 required hospitalization and a mortality rate of 33% . Since there is no significant difference between the survival of lung cancer patients infected with COVID-19 and the survival of advanced lung cancer due to late presentation, even in lung cancer patients who are candidates for surgery, if the perioperative risk of COVID-19 is greater than 13%, the operation may be delayed. Still, immediate surgery increases survival if there is a low risk of COVID-19 . For this reason, it is crucial to arrange centers where the diagnosis and treatment of lung cancer patients can be carried out, even during the most intense periods of restrictions during the pandemic period. Considering that epidemic diseases such as COVID-19 can exist in any period, necessary precautions should be taken beforehand.
There are some limitations of our study. Firstly, it is a study that includes only one center from Turkey. Secondly, the pathological diagnoses, stages, and treatments of the patients could not be documented. For this reason, although it was shown that there was a decrease in the number of admissions, patients' cancer stages and whether the cancer treatment was affected could not be demonstrated. Third, we do not know whether the patients were infected with COVID-19 and caused late admission.