Modeling tumor and treated lung volume influences in the irradiation of non-small-cell lung cancer patients

Concurrent chemoradiotherapy for stage III non-small-cell lung cancer: recent progress and future perspectives (a narrative review)

Concurrent chemoradiotherapy (CHRT) remains the therapeutic standard for locally advanced inoperable non-small-cell lung cancer (NSCLC). The median overall survival (OS) with this approach is in the range of 20–30 months, with five-year survival of approximately 30%. These outcomes have recently been further improved by supplementing CHRT with maintenance durvalumab, a monoclonal anti-PD-L1 agent. The progress in treatment outcomes of locally advanced NSCLC before the era of immunotherapy has been achieved mainly by virtue of developments in diagnostics and radiotherapy techniques. Routine implementation of endoscopic and endobronchial ultrasonography for mediastinal lymph nodes assessment, positron emission tomography/computed tomography and magnetic resonance imaging of the brain allows for more accurate staging of NSCLC and for optimizing treatment strategy. Thorough staging and respiratory motion control allows for higher conformity of radiotherapy and reduction of radiotherapy related toxicity. Dose escalation with prolonged overall treatment time does not improve treatment outcomes of CHRT. In consequence, 60 Gy in 2 Gy fractions or equivalent biological dose remains the standard dose for definitive CHRT in locally advanced NSCLC. However, owing to increased toxicity of CHRT, this option may not be applicable in a proportion of elderly or frail patients. This article summarizes recent developments in curative CHRT for inoperable stage III NSCLC, and presents perspectives for further improvements of this strategy

Challenges in optimizing chemoradiation in locally advanced non small-cell lung cancers in India

Data supporting use of concurrent chemoradiation in locally advanced lung cancers comes from clinical trials from developed countries. Applicability and outcomes of such schedules in developing countries is not widely reported. There are various challenges in delivering chemoradiation in locally advanced non small cell lung cancer in developing countries which is highlighted by an audit of patients treated with chemoradiation in our center. This article deals with the challenges in the context of a developing country. We conclude that sequential chemoradiotherapy is better tolerated than concurrent chemoradiation in Indian patients with locally advanced non-small cell lung cancers. Patients with stage IIIa, normal weight or overweight, and adequate baseline pulmonary function should be offered concurrent chemoradiation.

Radiochemotherapy in special populations with limited-disease small-cell lung cancer and locally advanced non-small-cell lung cancer

SUMMARY The evidence to date confirms that concurrent radiochemotherapy (RT–ChT) is the treatment of choice in small-cell lung cancer and locally advanced non-small-cell lung cancer. But these patients require a good performance status and an interdisciplinary group of clinicians, which is hard to find at some facilities around the world. Socioeconomic differences worldwide, inadequate tolerance to RT–ChT, tobacco comorbidities, the high percentage of elderly patients and their low level of recruitment in clinical trials could explain, in part, the reason why lung cancer still remains the leading cause of cancer-related death around the world. This review focuses on RT–ChT in a special population of eldery, comorbid patients and populations with limited resources from developing countries with locally advanced non-small-cell lung cancer and limited-disease small-cell lung cancer.

Lung cancer management in limited resource settings: guidelines for appropriate good care

Lung cancer is a major cause of cancer death worldwide and is becoming an increasing problem in developing countries. It is important that, in countries where health care resources are limited, these resources are used most effectively and cost-effectively. The authors, with the support of the International Atomic Energy Agency, drew on existing evidence-based clinical guidelines, published systematic reviews and meta-analyses, as well as recent research publications, to summarise the current evidence and to make broad recommendations on the non-surgical treatment of patients with lung cancer. Tables were constructed which summarise the different treatment options for specific groups of patients, the increase in resource use for and the likely additional clinical benefit from each option. These tables can be used to assess the cost-effectiveness and appropriateness of different interventions in a particular health care system and to develop local clinical guidelines.

Early stage medically inoperable non-small cell lung cancer

A nihilistic approach to the treatment of patients with medically inoperable, early stage non-small cell lung cancer (NSCLC) is not warranted. Despite the frequency of comorbid medical illness in patients with medically inoperable NSCLC, lung cancer progression is the major cause of morbidity and death. Although expectations for cure are reduced compared to good-risk patients (eg, adequate pulmonary reserve), modest long-term survival rates of patients have been reported, after definitive therapy. A comparison of radiotherapy and limited resection is difficult because of the lack of randomized data and the selection bias inherent in retrospective reports. For example, patients treated with surgery have peripheral lesions, undergoing rigorous staging compared to patients treated with radiotherapy. In a multidisciplinary thoracic program, patients are counseled on the options of sublobar resection and conformal radiotherapy. The efficacy of adjuvant radiotherapy, after limited resection, in reducing local recurrence in patients with medically inoperable NSCLC is unclear. However, adjuvant radiotherapy may be considered if a postoperative target volume can be defined, particularly if resection margins are narrow. Considering the benefit of chemoradiotherapy for patients with locally advanced disease, combination therapy is administered to patients with good performance status and large (eg, > 4 cm) primary lesions, although combined therapy may increase the potential for pulmonary toxicity in patients with baseline pulmonary dysfunction. Prospective data are becoming available to define the value of treatment alternatives for patients with medically inoperable NSCLC. The Cancer and Leukemia Group B completed a phase II study of thoracoscopic wedge resection and postoperative radiotherapy, whereas a phase I trial of dose-intensive accelerated conformal radiotherapy is ongoing. Trials involving systemic therapy for patients with medically inoperable NSCLC should be developed.

Accelerated hypofractionation for early-stage non-small-cell lung cancer

PURPOSE

To describe the outcome of treating early-stage non-small-cell lung cancer (NSCLC) with an accelerated hypofractionated course of radiotherapy.

METHODS AND MATERIALS

A policy of treating early-stage NSCLC with a dose of 48 Gy in 12 once-daily fractions without elective irradiation of radiologically uninvolved regional nodes was adopted in 1996. We describe the outcome in 33 patients with NSCLC treated with this dose-fractionation schedule.

RESULTS

The median patient age was 72.0 years. Most patients (75.8%) were not surgical candidates because of medical comorbidities or old age. For staging, 97.0% underwent CT of the thorax, and mediastinoscopy was performed in 6.1%. All patients had Stage T1-T2N0, except for 4 patients with positive nodes based on pathologically involved or clinically enlarged lymph nodes adjacent to the primary tumor. The overall survival rate was 80.1% at 1 year and 46.0% at 2 years. The median survival was 22.6 months. The cause-specific survival rate was 89.8% at 1 year and 54.1% at 2 years. The recurrence-free survival rate was 66.4% at 1 year and 40.0% at 2 years. Lateral radiotherapy field margins of <2 cm predicted for inferior overall survival, cause-specific survival, and recurrence-free survival on univariate and multivariate analyses (p <0.05). The most commonly reported toxicities were acute dermatitis (30.3%) and late cutaneous/subcutaneous fibrosis (24.2%).

CONCLUSION

Accelerated hypofractionation for early-stage NSCLC appears to be safe and produces promising early results. Very small radiotherapy field margins may lead to an inferior outcome. Prospective studies are needed to determine the optimal dose-fractionation schedule.

Influence of tumor volume on survival in patients irradiated for non-small-cell lung cancer

PURPOSE

To investigate the importance of CT-defined total tumor volume (TTV) on overall survival (OS) in patients with unresectable or medically inoperable non-small-cell lung carcinoma (NSCLC).

METHODS AND MATERIALS

Between 1991 and 1998, 150 evaluable patients with Stage I-IIIB NSCLC were treated with three-dimensionally planned conformal radiotherapy and curative intent at Duke University Medical Center. On the treatment-planning CT, the primary tumor and nodal volumes were identified and subsequently combined to form the TTV. The TTV was compared with the stage and outcome with respect to OS, local progression-free survival, and distant failure-free survival using the Kruskall-Wallis analysis of variance and Kaplan-Meier actuarial method. To account for the potentially confounding effects of therapeutic and patient-specific covariates on survival, the Cox proportional hazard regression model was used.

RESULTS

The TTVs in patients with Stage I disease (median 19 cm3) were smaller than in patients with Stage II (median 80 cm3) or Stage III (median 97 cm3; p <0.001) disease. The Stage II TTVs were not significantly different from those of Stage III (post-hoc test according to Bonferroni). Prolonged OS was independently associated with a small TTV (<80 vs. >80 cm3 [median]; p = 0.01), young age (<60 vs. > or =60 years; p = 0.03), high Karnofsky performance status (< o r =70 vs. >70; p = 0.04), and female gender (p = 0.04). Both stage (p = 0.7) and T stage (p = 0.06) were of less importance for OS than was the TTV, according to multivariate modeling. Increased local progression-free survival (p = 0.001) and distant failure-free survival (p = 0.03) were independently associated with a small TTV (i.e., <80 cm3). The results were unchanged if the TTV was analyzed as a continuous variable.

CONCLUSION

A strong independent association between a small CT-defined TTV and prolonged survival in patients with NSCLC selected for curative/definitive RT was found. Future therapeutic studies in NSCLC should consider stratifying/adjusting for differences in TTV to avoid confounding effects on survival from variations in the TTV at baseline.

Hypofractionated irradiation for non-small cell lung cancer

Large radiation fractions are an effective way of killing tumour cells but have generally been avoided in curative treatment of patients because of concerns of a disproportionate increase in late normal tissue toxicity. Radiobiological modelling of the effect of radiation on lung tumours and late-reacting normal tissues, which are more sensitive to large radiation fractions, has been undertaken. The biological effect of radiation on tumours is increased as the overall treatment time is shortened but this is not true for late-reacting normal tissue. Sample data are shown in which the relative increases in radiation effect on the tumour and late-reacting normal tissues are similar after hypofractionation. A favourable therapeutic ratio can be achieved because the bulk of normal tissue will receive a lower dose of radiation at a lower dose per fraction than the tumour, especially with current techniques where the volume of normal tissue irradiated can be sharply reduced. The clinical evidence confirms that lung toxicity is volume-dependent. It is the small Stage I and II tumours which are most likely to benefit from hypofractionated regimens, as the volumes to be treated are smaller and they have a lower incidence of distant metastases. Patients with Stage III tumours with favourable prognostic factors are nowadays treated with combined chemotherapy and radiotherapy and so for this group more conservative hypofractionation regimens are being explored. However, more advanced tumours may be treated with hypofractionation to lower total doses to achieve palliation and a modest degree of survival benefit.