RAMB - Setembro 2017

uidelines

for

the

treatment

lung

cancer

using

radiotherapy

ssoc

ras

2017; 63(9):729-732

731

with 90% of patients without treatment-related pneu-

monitis, versus conformal radiotherapy, with 75% free

of this toxicity.

(B)

Toxicity to normal tissue is the major obstacle to be dodged

in order tomake it possible to release a suitable dose, aiming

at better tumor control. One of the tissues most sensitive to

radiation is the lung. Depending on the lung volume receiv-

ing a given dose, as well as other factors (pulmonary reserve,

radiobiological factors, concomitant therapy), patients may

not present with acute symptoms, but only asymptomatic

pulmonary fibrosis evidenced in the radiation field (typi-

cally 12months or longer after treatment), transient moder-

ate pneumonitis (typically 2-6 months after radiotherapy),

or a more symptomatic, severe, or even fatal disease. Thus,

volumetric parameters such as V20 (percentage of pulmo-

nary volume receiving ≥ 20 Gy), V10 and V5, and pulmonary

mean dose have been shown to be the most important

predictive factors for severe pulmonary toxicity.

14,16-18

The lung is the thoracic organ most sensitive to the

deleterious effects of radiation, but this does not mean

that it is the only limiting anatomical structure to restrict

the appropriate dose release. Spinal cord, esophagus, and

heart are also restrictive. The spinal cord, for example,

should be protected from doses > 45 Gy.

The esophagus does not have a critical dose limit such

as the spinal cord, but acute damage caused by radiation

can be identified even at modest doses depending on the

volume irradiated. Significant esophageal morbidity is

routinely reported, which often limits the administration

of an appropriate treatment, using optimal dose and

without interruptions, especially if concomitant with

chemotherapy and/or whenever mediastinal lymph nodes

should be addressed.

19,20

A recently published retrospective study with 223

patients showed that the rate of patients with severe

esophagitis requiring feeding tube was 5% with IMRT

versus 17% with conformal radiotherapy (p=0.005).

(B)

3. I

there

impact

quality

life

that

justifies

the

use

IMRT

compared

conventional

and

conformal

radiotherapy

One of the goals when we offer a modality of treatment for

any type of cancer is the preservation or improvement of

the patients’ quality of life. However, because it is an out-

come that is difficult to assess due to both subjectivity and

the scarcity of objective tools for its measurement, there is

little information on the subject.

The best study that evaluated the impact on quality

of life of lung cancer patients treated with different ra-

diotherapy techniques was published as a summary, not

providing the full text. This was a randomized clinical

trial whose main objective was to evaluate the impact of

treatment on the survival of patients with locally advanced

lung cancer after high-dose radiotherapy (60 Gy x 74 Gy).

As a secondary outcome, information regarding quality

of life was prospectively collected using instruments

validated for patients with lung cancer, and the following

results were found:

(A)

1. Of the 419 patients included in the study, 45% under-

went IMRT and 55% underwent conformal radiother-

apy. The two groups were equally distributed in terms

of patient characteristics, except for tumor size that

tended to be larger in the IMRT group.

2. In all, 357 patients completed the questionnaires to

assess quality of life before treatment. The question-

naires used were as follows: “Functional Assessment

of Cancer Therapy-Trial Outcome Index” (FACT-TOI),

“Physical Well Being” (PWB), “Functional Well Being”

(FWB) and “Lung Cancer Subscale” (LCS).

3. Twelve (12) months after the end of treatment, pa-

tients who underwent IMRT presented better quality

of life than those treated with conformal radiotherapy,

according to all of the questionnaires evaluated. All dif-

ferences were statistically significant.

4. I

there

difference

effectiveness

local

control

overall

survival

between

IMRT,

conformal

and

conventional

radiotherapy

Based on a comparison between IMRT and conformal

radiotherapy for lung tumors, two studies evaluated dis-

ease control and survival outcomes:

1. A retrospective study included 223 patients with

small cell lung cancer and evaluated two consecu-

tive historical cohorts. The authors found no dif-

ference in local control, locoregional control, inci-

dence of distant metastases, disease-free survival,

and overall survival for patients undergoing chemo-

therapy and IMRT compared with conformal radi-

ation therapy.

(B)

2. Another retrospective study included 496 patients

with non-small cell lung cancer and assessed two con-

secutive historical cohorts. The authors found better

overall survival for patients undergoing concomitant

chemotherapy and IMRT compared with conformal

radiation therapy. In this study, median survival was

16.8±16.3 months with IMRT and 10.2±6.4 months

with conformal radiotherapy (hazard ratio = 0.64 [0.41-

0.98], p=0.039).

(B)