This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Screening, Subject name: Social & Preventive Medicine
If rapidly progressive cancers are missed by a screening test, which type of bias will occur? 
Select and explain. 
A. Lead-time bias, B. Length bias, C. Selection bias, D. Surveillance bias
B: Length bias
Answer: B: Length bias 
Explanation: Length time bias is a form of selection bias Fast-growing tumours generally have a shoer asymptomatic phase than slower-growing tumours. Thus, there is a shoer period of time during which the cancer is present in the body. As a result, if the same number of slow-growing and fast-growing tumours appear in a year, the screening test detects more slow-growers than fast-growers. If the slow-growing tumours are less likely to be fatal than the fast growers, the people whose cancer is detected by screening do better Ref : Park 23rd edition Pgno : 74