目標：熵在熱力學的領域中，指的是失去的熱量或無法利用的能量的量測，應用於人口 學中，其可視為生命表中損失之人年數相對於平均餘命之比率，若喪失的人年數的比率(熵) 愈小，則人們所能生存的平均餘命(功)就會愈大，反之則會愈小。本文旨在探討出生及中、老 年時期生命表熵及惡性腫瘤熵之變化趨勢。方法：闡述說明生命表中平均餘命，死亡率變化 速率與熵的關係及其特性，並利用台灣生命表相關資料探討生命表熵及疾病熵(惡性腫瘤)變化 趨勢。結果：研究結果顯示1952年至2014年生命表熵H0(0歲熵)男、女性皆呈平穩曲線下降， H40(40歲熵)男、女性則有震盪起伏現象，H65(65歲熵)是震盪起伏上升，幅度較H40為大；HE係 指因死亡率減少所能增加的平均餘命，其變動趨勢顯示HE0呈現下降趨勢，而在HE40與HE65則 是上升的；1975年至2014年惡性腫瘤熵，男、女性均呈上升趨勢，其對平均餘命的影響亦然。 以2014年平均餘命推算，若當年所有死亡率悉數去除(免死一次)，則男、女性平均壽命分別為 89.8年及94.92年。結論：本研究初步檢視生命表中熵的變動趨勢，發現中、老年人熵值高(特 別是中年人)，意謂較少的系統能量可以轉化為功(存活的生命年數)，因此延遲老化應是未來努 力的目標；惡性腫瘤熵男、女均呈上升趨勢，且男性高於女性。另外，2014年資料顯示，惡性 腫瘤熵影響中年時期的減損甚鉅，顯然中年時期的預防應重於一切，至於其對老年男、女性平 均餘命的影響分別為18%及10.7%，亦不容小覷。延遲衰老及癌症預防應列為政府健康促進政 策要務。(台灣衛誌 2016；35(5)：477-486)

Objectives: In thermodynamics, entropy is heat loss or lack of availability of thermal energy needed for activity within a given operating system. It is viewed as the percentage of the average years of future lost by the observed deaths to the life expectancy in Demograph. If loss of person-years is less, then people will survive longer, and vice versa. This study aimed to evaluate the long-term trends in entropy and cancer entropy at birth, middle age and advanced age in Taiwan. Methods: Interpret how the life table entropy derived from the relationship between the proportional rate of progress in force of mortality and life expectancy. The Taiwan life table and cancer data set was used to explore long-term trends in entropy and cancer entropy based on number of deaths recorded at birth, middle age and older age (age 65 years and older). Results: From 1952 to 2014, trends in birth entropy for males and females declined steadily; at middle age, trends in entropy for males and females fluctuated up and down; trends in entropy among older adults was similar to middle age fluctuated up and down but with a wider margin. Mortality rates are declining in all age groups, while life expectancy is increasing for both sexes. From 1975 to 2014, trends in cancer entropy and life expectancy affected by cancer were increasing for both sexes. In 2014, life expectancy was estimated to be 89.8 and 94.92 years at birth for males and females, respectively, when the mortality rate is reduced completely (saved from death once) for the whole first year. Conclusions: This study found a high percentage of entropy in middle aged and older adults, showing that loss of person years is higher for middle-aged men and women especially. Trends in cancer entropy are rising and are higher among males than females. In 2014, cancer entropy was the major effect on middle age life expectancy. However, the effects of cancer on life expectancy among older adults (18% for males, 10.7% for females) should still not be overlooked. Results suggest that reducing senescence and cancer prevention should be the main purpose of long-term health promotion by the government in the future. (Taiwan J Public Health. 2016;35(5):477-486)