The positive revenue guidance suggests that NovoCure is performing better than the market anticipated, which typically results in increased investor confidence and a rise in stock price. Given that revenue guidance is a significant indicator of a company's financial health and future prospects, this news is highly relevant and important to investors. The confidence score is high due to the direct correlation between positive revenue guidance and stock performance, although it is not at the maximum because market conditions and other unforeseen factors can affect stock prices.