However, it should not be overlooked that the death rate for some forms of cancer shows a dual-peak phenomenon. Besides the peak period among the elderly, there is another peak among middle-aged people. For example, the death rate from oral cancer is very high for men aged 55-59, while that for breast cancer is high among women aged 45-49. This phenomenon is related to the increase in risk factors at these ages.
不可忽視的是，部份癌症的死亡率出現「雙高峰期」，除了老年的高峰期外，在中年時亦出現一個高峰期，像男性的口腔癌在五十五到五十九歲；女性乳癌在四十五到四十九歲，都有一個高峰期，而此一高峰期與危險因子增加關連較多。