癌の化学療法

CHEMOTHERAPY OF CANCER

はじめに

　現状では早期診断，手術こそ制癌への最良の方策である．診断技術の驚異的な進歩は，より早期の癌の発見，治療を可能にして来た．伊藤の報告¹⁾によれば粘膜内，粘膜下層に限局するいわゆる早期胃癌224例の摘出胃の組織学的検索では，8％に血管浸潤，22％に所属リンパ節転移が認められているにもかかわらず，これらの5年生存率は90％以上の好成績を示している．これは時宜にかなった早期診断，早期手術が迅速に行なわれたことを意味している．しかし，以上の成績はひとたび時期を失すれば，たちまち周囲他臓器への浸潤，転移を来たしうる要因をはらんでいるものとして，癌を局所の疾患として扱うことの困難さをも示している，事実，過去7年間，国立がんセンターで行なわれた胃癌手術例中，早期胃癌は15％に過ぎず¹⁾，執拗な浸潤・転移の様相は癌を全身疾患として把握しなければならない立場に立っことを余儀なくしている．全身治療を行ないうる可能性を持っている化学療法への期待は絶大なものがある．期待の実現化のために努力の方向をどこに求むべきか，現在のわれわれに課されている大きな問題である．

　薬剤による癌征服への戦略には，2つの道が考えられる．1つは発癌機構を明かにし，そこで得られた知見を治療に向けようとするものである．しかし，正常細胞と異なる腫瘍細胞の特徴が解明されない限り，現状では腫瘍細胞のみを崩壊せしめ，正常細胞にはなんらの障害を与えることのない薬剤を求めることは，不可能である．他の1つはこうした制約のなかで，さまざまな工夫のもとに，現在使用することのできる薬剤の効果をより一層高めようとする努力である．われわれ臨床家の努力は多く後者の立場から払われている．

　In order to grasp some tangible clues to the enhancement of effectiveness of cancer chemotherapy, its various aspects such as behavior of tumor, mode of medication and the physical state of the host have been investigated, centered on effective cases picked out of 360 cancer cases recently treated with chemotherapeutic agents by the authors.

　Main factors on the tumor side influencing the effectiveness of chemotherapy are size and spread of cancer at the time of therapeutic inception. As for mode of medication, it is presumed that intermittent administration of large dosis within the limit of permissible one is favorable, as is shown by the results of experiments. It also has been shown that co-administration of another agent having different mechanism of action is superior to single medication. Effective cases are more numerous when the condition of the host is not greatly influenced by the spread of tumor; in some cases efficacy of life prolongation was recognized, though of short duration.

　Self-evident as it is to demand newer types of anticancerous agents, it further remains to establish an appropriate method to find out the sensitivity of tumor against chemotherapeutic agents, as is necessary for selection of medication, and also to determine some practical way of application to heighten the resisting power of the host. For exploitation of any definite procedure for improving efiicacy of medication, it is of necessity not only to correlate tumor, medication and the the ho? with one another, but also to undertake comprehensive investigation based on the correlation.

　It has been biochemically proved by the authors that lysosome granules in tumor cells are involved in their process of destruction through anticancerous agent. Furtheremore, it has been established that combined use of lysosome labilizer further improves the effect of chemotherapy of cancer.

　In this paper reference is also made to the results of experiments in combined use of various labilizers and anticancerous agents as well as to notable results obtained in their clinical applications.