Lung cancer will strike about 61,000 persons and cause 55,000 deaths in the United States this year. About 46,000 victims will be men and 9,000, women. A rare disease at the turn of the century, lung cancer has increased sharply, principally because of increased cigarette smoking. The most common warning signal is a persistent cough or lingering respiratory ailment. Although lung cancer is detectable with X-ray, by the time it can be seen it is usually too far advanced to be controlled by presently known methods. Only about 7 percent of all lung cancer patients survive 5 years.
The outlook for patients with lung cancer continues to be poor. Of the 61,000 people it will strike this year, 55,000 will die, the largest group to die from cancer of a single site in the United States.
According to the classification system of the World Health Organization, there are five types of lung cancer: epidermoid carcinoma, small cell carcinoma, adenocarcinoma, large cell undifferentiated carcinoma, and combined epidermoid and adenocarcinoma.
Surgery is the treatment of choice, since complete excision of a circumscribed lesion offers the only real chance for cure. However, 65 to 80 percent of patients cannot be treated surgically either because at diagnosis their disease is too widespread or they are too ill to undergo an operation.
Patients whose disease is considered inoperable seem to have a slightly better outlook for survival if treated with radiotherapy rather than general supportive care. In some patients, radiotherapy may make the tumor susceptible to surgical removal. Irradiation by supervoltage equipment or cobalt apparatus appears more beneficial than conventional X-ray.
Several drugs exert an antitumor effect on lung cancer but their benefits are usually more transient than those gained by radiotherapy. Two alkylating agents, cyclophosphamide and nitrogen mustard, have been evaluated for possible effectiveness. In one study, cyclophosphamide appeared to produce survivals of comparable duration to those of patients receiving radiotherapy; nitrogen mustard was less effective.
In a study reported in March 1968 by scientists of the University of Toronto, 40 patients with advanced lung cancer considered inoperable and unsuitable for radiotherapy were treated with large, intermittent doses of cyclophosphamide. Excluded from the study were patients with adenocarcinomas, since this well-differentiated tumor is believed to be unresponsive to chemotherapy. An interval of about 3 weeks between doses of cyclophosphamide was scheduled to permit complete recovery of bone marrow cells. Of 35 patients considered evaluable at the time of reporting, 14 (40 percent) showed objective evidence of tumor regression. The median survival for the 35 patients was 126 days. The median survival for the entire group was 142 days. These results are markedly better than a median survival time of 54 days achieved among a group of 50 patients treated with nitrogen mustard earlier at the same medical center.
In another recent study of 342 patients with inoperable lung cancer treated at eight medical centers, dactinomycin and 5-fluorouracil (5-FU) were evaluated for possible usefulness as adjuncts to radiotherapy. Neither of these drugs, given by rapid injection prior to and in conjunction with radiotherapy, was able to improve the survival time of these patients. Patients treated with radiotherapy alone had a median survival of 136 days; those receiving X-ray plus 5-FU, 133 days; and those receiving X-ray plus dactinomycin, 105 days.
Metastases from lung cancer frequently occur in the pleural cavity and cause an accumulation of fluid which may greatly add to the discomfort of the patient. The instillation of an alkylating agent such as thioTEPA, or quinacrine (Atabrine), or a radioactive isotope of gold or phosphorus may eliminate or reduce these pleural effusions and relieve symptoms, even though the basic course of the disease is not altered.
A preliminary evaluation of the drug hydroxyurea in inoperable lung cancer was reported early in 1968 by clinical investigators at various Veterans' Administration hospitals. They noted that a group of 157 patients receiving the drug appeared to have a slightly longer survival time than a similar control group receiving an inert compound. It can be seen from the above studies that negligible progress has been made in the chemotherapy of lung cancer.