Patient survival for many malignancies is mainly dependent on the stage of the disease. The most important reason underlying the discrepancies of the curative rates between China and developed countries is that early cancer detection rates are pretty low for most of the cancer types in China. For operable gastric cancers in China, stage I diseases only account for 18%, and approximately 59% are stage III–IV diseases . Contrastingly, in Japan, early detection rates are very high, with over 60% of stage I diseases and 24% of stage III–IV diseases . For breast cancer, stage I diseases account for only 13.5% of all cases in China, in contrast, it is 50.5% in the US . For colorectal cancer, early detection rates in large city hospitals in China is 30% , whereas the average in the US is 38.5% . Clearly, more endeavors need to be made to significantly increase the early detection rates of major cancers in China.
The application of cancer screening for major cancers in healthy populations using current medical technologies is impeded by two main difficulties. The first difficulty is the expensive cost of current technologies. Due to limited financial resources, the state-owned medical insurance agencies for most Chinese people cannot cover the annual workup for major cancers using traditional technologies, e.g., chest X-ray for lung cancer, let alone using more accurate yet expensive technologies, e.g., low-dose computed tomography scanning for lung cancer. Another difficulty is the limited number of healthcare practitioners in China to complete population-based screening for major cancers using traditional technologies, which are highly dependent on professionals for operation .
Some novel and inexpensive technologies need to be invented to simultaneously overcome these two difficulties in China and other developing countries facing similar challenges. Encouragingly, several promising techniques for at-home cancer screening have been approved for clinical practice in the US. By detecting tumor specific KRAS mutations, abnormal NDRG4, and bone morphogenetic protein 3 (BMP3) methylation, plus hemoglobin immunoassays of stool samples, a company named Exact Sciences has developed an at-home screening kit for detecting colorectal cancer, as well as advanced precancerous lesions, with satisfying sensitivity and specificity . For cervical cancer screening, technologies based on self-collected vaginal samples for human papillomavirus infection (HPV) testing are available and currently under clinical validation [14, 15]. More promisingly, highly sensitive nanoarray sensors for exhaled volatile organic compounds have recently been developed for early detection of lung cancer using breath samples, which can even detect epidermal growth factor receptor (EGFR) mutation for differential diagnosis [16, 17].
Before widespread use of at-home screening technologies in China, validation trials need to be conducted to optimize the techniques and to customize the analytical criteria for the Chinese population. These endeavors could be made by establishing several institutions in different parts of the country responsible for conducting clinical trials, optimizing screening systems, and routinely testing and storing the samples.