Increasing evidence that non-small cell lung cancer is a systemic disease from the outset confirms the rationale for adjuvant chemotherapy. However, clinical trial evidence of benefit is still awaited. The position is clearer in the case of neoadjuvant therapy because long-term follow up of two trials now shows that patients randomized to chemotherapy before surgery were significantly more likely to survive to 5 years than patients treated with surgery alone. Early data suggest that neoadjuvant chemotherapy based on docetaxel (Taxotere; Aventis, Antony, France) (possibly used sequentially with other agents) may be as effective as older regimens and better tolerated. Because p53 status influences the expression of microtubule-associated proteins and hence the sensitivity of a tumor to taxanes, it is possible that molecular markers could be used to customize chemotherapy to individual patients. Generally, it is becoming clearer that molecular staging is a more sensitive means of demonstrating tumor dissemination than light microscopy. The Cancer and Leukemia Group B is undertaking a prospective study using reverse transcriptase-polymerase chain reaction to detect MUC-1 RNA in bone marrow and hilar and mediastinal lymph nodes removed at resection with the aim of distinguishing between stage I patients likely to remain disease-free for long periods and those at high risk of relapse. A study of small cell lung cancer is using automated fluorescence microscopy to detect keratin-positive cells in the marrow and blood of patients who have a complete response to initial therapy but are nevertheless at high overall risk of relapse. The identification of genetic lesions in a high proportion of patients with non-small cell lung cancer may guide the development of new therapies aimed at increasing rates of apoptosis among tumor cells.