5．レーザー（光線力学療法）

Photodynamic Therapy

光線力学的治療（photodynamic therapy：PDT）とは，腫瘍に取り込まれる薬剤（光感受性物質）とそれに対応する波長のレーザー光により反応を生じさせ，腫瘍選択的に殺細胞効果を引き起こす，中心型早期肺癌に対する侵襲の少ない標準的治療として確立されている．中心型早期肺癌患者のほとんどが重喫煙者であるため，肺気腫や心疾患などを合併し心肺機能が低下していることが多い．また，中心型早期肺癌は同時性・異時性に多発することが知られている．このような患者背景を思惟すると，肺機能を失わないPDTは第一に考慮すべき治療といえる．PDTの現状と今後の展望について概説する．

Photodynamic therapy （PDT） is a method consider “medical treatment” in which a drug （i. e., photosensitizer） is incorporated into a tumor and a laser beam of a wavelength corresponding thereto generates a reaction consider “elicits a phototoxic reaction that kills the tumor cells”. It is a less invasive treatment that has a tumor-selective cell killing effect and has been established as a standard therapy for centrally located early stage lung cancer. Most patients with centrally located early stage lung cancer are heavy smokers, and cardiopulmonary function is often deteriorated owing to pulmonary emphysema or heart disease. Centrally located early stage lung cancer is known to occur frequently as synchronous or metachronous neoplasm. Taking the patient’s background into consideration, PDT that does not affect the pulmonary function may be considered as a promising treatment. Herein, we outline the current applications of PDT and its future prospects.