Are More Aggressive Therapies Able to Improve Treatment of Locally Advanced Non-Small Cell Lung Cancer: Combined Modality Treatment?

[Novel irradiation techniques in the treatment of solid tumours. Radiotherapy for metastases]

Novel developments in percutaneous radiotherapy, such as positron emission tomography/computed tomography, adaptive radiation planning, intensity modulation radiotherapy and intensity modulated arc therapy (RapidArc), as well as the newer generation of image control (cone-beam computed tomography) and image guided radiotherapy ensure increased dosages of planning target volume and clinical target volume of solid tumours without damaging surrounding tissues and providing maximal protection. By raising the dosages of planned target volume and clinical target volume, these novel technical developments have created new indications in the treatment of solid tumours. With the aid of the cone-beam computed tomography and image guided radiotherapy the organ metastasis (lung, liver, spinal cord) and the primary tumour can be treated safety and effectively. Hypofractionation, dose escalation and the use of stereotactic devices can probably decrease radiation damage. The authors review the most common forms of evidence-based fractionation schemes used in irradiation therapy.

Is stereotactic ablative radiotherapy an alternative to surgery in operable stage I non-small cell lung cancer?

Surgery is the gold therapeutic standard for patients affected with stage I non-small cell lung cancer. Stereotactic ablative radiotherapy is currently considered the preferred treatment option for inoperable patients, representing approximately 25%. Limited data are available directly comparing surgery and SABR in operable patients, none of them prospective. Preliminary results are encouraging, showing that the two treatment modalities are equally effective in terms of tumour control, with expected similar survival projections. Moreover, in elderly patients SABR could represent a valid treatment alternative in comparison to surgery due to the lower morbidity. We here review and discuss the potential role of SABR as an alternative to surgery in operable early stage lung cancer patients.

A planning study of radiotherapy dose escalation of PET-active tumour volumes in non-small cell lung cancer patients

BACKGROUND

Patients with non-small cell lung cancer (NSCLC) have poor prognosis partly because of high local failure rates. Escalating the dose to the tumour may decrease the local failure rates and thereby, improve overall survival, but the risk of complications will limit the possibility to dose-escalate a broad range of patients. Escalating only PET-active areas of the tumour may increase the potential for reaching high doses for a variety of tumour sizes and locations.

MATERIAL AND METHODS

Ten patients were randomly chosen for a dose escalation planning study. A planning target volume (PTV) was defined on the mid-ventilation scan of a four-dimensional computed tomography (4D-CT) scan and a boost planning target volume (PTV-boost) was defined based on a positron emission tomography computed tomography (PET-CT) scan. Treatment plans were created aiming to reach the highest achievable of 74 Gy, 78 Gy or 82 Gy in 2 Gy per fraction prescribed to the PTV-boost without compromising normal tissue constraints and with the PTV prescribed in all cases a biological equivalent dose in 2 Gy fractions of 66 Gy.

RESULTS

Nine of ten patients could be escalated to the highest dose level (82 Gy), while one patient was limited by the oesophagus dose constraint and could only reach 74 Gy. Four patients could be dose-escalated above 82 Gy without compromising normal tissue constraints.

CONCLUSION

Dose-escalating only the PET-active areas of lung tumours to doses of 82 Gy while respecting normal tissue constraints is feasible, also in a series of unselected patients including cases with relatively large tumours.

Lung cancer: Future directions

Increasingly, basic research is being translated into clinical benefits for patients. Recent studies have shed more light on the clinical use of targeted therapies such as tyrosine kinase and angiogenesis inhibitors, and predictive factors for their clinical benefit and their role in different clinical settings are now being elucidated. New insights into the basic biology of lung cancer hold translational promise in risk assessment, early detection, molecular staging, treatment response prediction and novel therapies. New targeted agents directed at apoptotic and developmental pathways have the potential to exploit newly discovered vulnerabilities in the basic machinery of cancer. In addition, exploration of the cancer stem cell phenomenon in lung cancer may generate new approaches to prevent recurrence in surgically respectable lung cancer, and for the long-term control of extensive disease. Molecular profiling may also allow for highly individualized prognostic, predictive and therapeutic treatment plans tailored for each patient based on the molecular diagnostic profile of their tumour. Advances in genetic susceptibility, early detection and individualized therapy based on each tumour's unique biological properties all hold promise for the future management of lung cancer.

Epidermal growth factor receptor inhibition and non-small cell lung cancer

The majority of non-small cell (NSC) lung cancers express epidermal growth factor receptor (EGFR). Many studies have evaluated the clinical effect from targeted therapy achieved by blocking EGFR in patients with NSC lung cancer. Treatment of biologically unselected patients with NSC lung cancer with two reversible quinazole EGFR inhibitors, gefitinib and erlotinib, gave negative results in all controlled trials but one. Ten percent to 20% of patients with NSC lung cancers have somatic mutations in EGFR, and these patients have a significantly higher response rate (73%) to treatment with EGFR inhibitors than patients with wild-type EGFR (10%). Patients with Asian background, women, non-smokers, and patients with adenocarcinoma had higher response rates than other patients, and the differences may be due to an association between the clinical characteristics and EGFR mutations. Further studies are needed to fully evaluate the effect of EGFR inhibitor-treatment for subgroups of patients with NSC lung cancer with favorable biological and clinical characteristics.