Joaquin G. Mira

Evaluation and radiotherapy implications of chest relapse patterns in small cell lung carcinoma treated with radiotherapy-chemotherapy: Study of 34 cases and review of the literature

The value of chest irradiation in small cell lung carcinoma (SCLC) has been recently questioned. To investigate this issue, we undertook a retrospective study of 34 cases of SCLC treated with chemotherapy and radiotherapy to the chest and brain. Emphasis was placed on analysis of patterns of chest disease relapse, chest complications, and sites of initial chest disease relapse in relation to volume treated by radiation. These results were compared with published reports. Of 17 cases with disease limited to the chest (LD), nine (53%) died of chest related complications, seven of these (41%) with chest disease recurrence. However, in five of these seven cases (72%), recurrences appeared initially outside the irradiated volume, in spite of 1–2 cm of safety margin, mostly in the ipsilateral lung, while the primary was without evidence of growth. Hence, chest disease relapse does not necessarily mean radiotherapy failure, as only 2 of the 17 cases (12%) had definite tumor growth in the irradiated field. This point is not properly emphasized in the literature, where marked discrepancies among authors reporting chest disease relapses are present. We elaborate about factors that will affect results, like frequency of follow‐up x‐rays, tumor size, site of chest disease relapse, and criteria to define tumor relapse. More autopsy and chest diagnostic studies are needed to investigate patterns of tumor spread within the lung. Survival alone is too broad a factor to measure the impact of radiotherapy in treatment. We need more understanding of the mechanisms of chest disease relapse to obtain a better design of radiotherapy ports. Systemic disease was the main cause of death in 17 patients with extensive small cell lung carcinoma, and routine chest irradiation cannot be justified although it might be of help for chemotherapy responders who are expected to have long survival.

Influence of chest radiotherapy in frequency and patterns of chest relapse in disseminated small cell lung carcinoma. A Southwest Oncology Group study

The value of radiotherapy to the chest (RC) in disseminated small cell lung carcinoma (SCLC) has been questioned. Two protocols for disseminated SCLC from the Southwest Oncology Group (SWOG) have been compared. They were developed four years apart. The first one included radiotherapy (RT), 3000 rad in two weeks, to the primary tumor, mediastinum and supraclavicular areas, while the second one deleted any RC. Multidrug chemotherapy (CT) and brain RT were used in both protocols. Nonresponders to CT were removed from the study. Our main findings are as follows: (1) Initial chest relapses (patients with no initial extrathoracic relapse) have increased from 24–55% when RC is not given (P = 0.0001). Overall chest relapse (adding those patients that relapsed simultaneously in the chest plus other sites) in the second protocol was 73%. (2) Amount of response to CT does not influence the chances for relapse. Even complete responders to CT have a high chance for chest relapse. (3) Sites of relapse without RC are mainly in the primary tumor, ipsilateral hilus and mediastinum. (4) With RC, relapses shift to the chest periphery, mostly to the lung outside the radiotherapy field and to the pleura. (5) The two very different CT regimens have produced similar percentages and duration of response. (6) CT schema with periodic reinductions prolongs duration of response and survival over schema with continuous maintenance. Hence, interruption of CT to allow RC does not seem to adversely influence CT efficacy. From our results and the review of the literature we conclude that: (1) patients with disseminated SCLC that respond to CT should be given RC to decrease chest relapses. (2) A dose of 3000 rad in two weeks seems to be enough to produce a low percentage of chest relapse in disseminated SCLC, as survival of these patients is short and many will die prior to developing chest relapse. However, according to the literature, 4000–4800 rad is probably a more effective dose. (3) More studies and guidelines are needed to outline proper boundaries of radiotherapy fields, to decrease chances of peripheral chest relapses. (4) Median survival might not be a good parameter to evaluate the impact of RC in disseminated SCLC. The study of long‐term survivors seems to be more important.

The value of radiotherapy for peyronie's disease: Presentation of 56 new case studies and review of the literature

Abstract Fifty-six patients with Peyronies Disease who were treated with radiotherapy at Penrose Cancer Hospital were studied retrospectively. All were treated with ortbovoltage, mainly with total dosages of 1000 to 1400 roentgens (from around 950 to 1330 rod), in 11 to 17 days. Penile induration was present in all patients; 87 % had curvature of the penis during erection and 70 % had pain during intercourse. After treatments, more than half the patients had complete resolution of pain. The overall response rate was 79%. The mean interval treatment-response was 2.8 months; 41% had already improved at the end of therapy or within one month afterwards. Improvement of induration and penile deviation was less successful; there were almost no complete responders and about 40 % had partial responses. Interval treatment-response was also longer (from 6 to 9 months). The size and location of the indurated placque did not influence response. The dosage, however, might influence the results; patients whose induration responded received a dose with a mean higher than non-responders. This difference was statistically significant. The duration of symptoms prior to treatment seems to be important. Eighty-one percent of responders had symptoms for less than five months; 76% of those with longer symptomatology did not benefit from irradiation. Failure by other methods of treatment did not preclude a response. Review of the literature shows that untreated patients have a benign course; a high percentage have eventual improvement or resolution of symptoms. However, spontaneous improvement occurs slowly and treatment seems to accelerate the process of recovery. Radiotherapy seems to be at least as successful as any other method of treatment. It should be recommended to patients who are troubled by their symptoms as a localized, painless, fast method of treatment, with no particular complications.

An electron beam pseudoarc technique for irradiation of large areas of chest wall and other curved surfaces

An electron beam technique has been developed for the treatment of large areas of the chest wall and other curved surfaces employing the stationary field electron beam mode ordinarily available on a linear accelerator. The technique simulates an arc through the use of multiple fixed fields. The electron collimator is not used. Field shaping is achieved through the combined effects produced by the photon jaw settings, the arc limits, and secondary lead shielding on the patients skin. Thus, there is no limitation on the circumferential extent of the field size that can be used. Electron beam energies of 6 MeV, 9 MeV, 12 MeV, 15 MeV and 18 MeV have been studied. Our findings indicate that, for these energies, this technique produces isodose curves parallel to the cylindrical surface at all depths beyond maximum build-up. This paper discusses the physical characteristics of the single beams, the degree of dose homogeneity achieved with the multiple fields, and the dosimetry technique developed to implement the therapy.

Influence of chest radiotherapy in frequency and patterns of chest relapse in disseminated small cell lung carcinoma

The value of radiotherapy to the chest (RC) in disseminated small cell lung carcinoma (SCLC) has been questioned. Two protocols for disseminated SCLC from the Southwest Oncology Group (SWOG) have been compared. They were developed four years apart. The first one included radiotherapy (RT), 3000 rad in two weeks, to the primary tumor, mediastinum and supraclavicular areas, while the second one deleted any RC. Multidrug chemotherapy (CT) and brain RT were used in both protocols. Nonresponders to CT were removed from the study. Our main findings are as follows: (1) Initial chest relapses (patients with no initial extrathoracic relapse) have increased from 24–55% when RC is not given (P = 0.0001). Overall chest relapse (adding those patients that relapsed simultaneously in the chest plus other sites) in the second protocol was 73%. (2) Amount of response to CT does not influence the chances for relapse. Even complete responders to CT have a high chance for chest relapse. (3) Sites of relapse without RC are mainly in the primary tumor, ipsilateral hilus and mediastinum. (4) With RC, relapses shift to the chest periphery, mostly to the lung outside the radiotherapy field and to the pleura. (5) The two very different CT regimens have produced similar percentages and duration of response. (6) CT schema with periodic reinductions prolongs duration of response and survival over schema with continuous maintenance. Hence, interruption of CT to allow RC does not seem to adversely influence CT efficacy. From our results and the review of the literature we conclude that: (1) patients with disseminated SCLC that respond to CT should be given RC to decrease chest relapses. (2) A dose of 3000 rad in two weeks seems to be enough to produce a low percentage of chest relapse in disseminated SCLC, as survival of these patients is short and many will die prior to developing chest relapse. However, according to the literature, 4000–4800 rad is probably a more effective dose. (3) More studies and guidelines are needed to outline proper boundaries of radiotherapy fields, to decrease chances of peripheral chest relapses. (4) Median survival might not be a good parameter to evaluate the impact of RC in disseminated SCLC. The study of long‐term survivors seems to be more important.

Dosimetry study of split beam technique using megavoltage beams and its clinical implications—I megavoltage beams and its clinical implications—I: 60Co beam, head and neck tumors

The problem of beam divergence and overlapping of adjacent fields in the treatment planning is well known. The use of split beam technique has been suggested as one way of addressing this problem. The present work reports a detailed dosimetry of this technique /sup 60/Co beam (Theratron 780). The dose distributions at and near the junction plane between two adjacent fields were measured; they were compared with those for diverging fields (with and without gap on the skin). As an illustration, different treatment planning techniques for head and neck tumors and subsequent dose distributions are discussed. Our findings clearly indicate that the extension of penumbra near the geometrical edge of a split beam is considerably less than that of an open beam of the same field size. Consequently when two adjacent fields are used, the overdose at and near the junction plane is reduced greatly by the split beam. For head and neck tumors the split beam technique gives a much better dose distribution than any other conventional treatment techniques.

Is it worthwhile to treat peyronie disease

Several articles describing the natural history of Peyronie disease have shown that untreated patients seem to have spontaneous improvement. It has been suggested that this could be the reason for the success of so many different methods. A review of the literature and of our previous experience has been done, trying to clarifying this issue. Our findings indicate that although treatment does not increase appreciably the percentages of amelioration of symptoms over the spontaneous evolution, it accelerates the improvement. Analysis is made of several factors which we have found to be important when making a decision for treatment: type of symptoms, psychologic impact of them, possible complications of the different therapy methods, and time interval from beginning of symptoms to treatment. The question of the worthiness of treating Peyronie disease does not have a single answer. We believe there are definite indications and several factors to be considered.

Dosimetry study of split beam technique using megavoltage beams and its clinical implications. I

The problem of beam divergence and overlapping of adjacent fields in the treatment planning is well known. The use of split beam technique has been suggested as one way of addressing this problem. The present work reports a detailed dosimetry of this technique /sup 60/Co beam (Theratron 780). The dose distributions at and near the junction plane between two adjacent fields were measured; they were compared with those for diverging fields (with and without gap on the skin). As an illustration, different treatment planning techniques for head and neck tumors and subsequent dose distributions are discussed. Our findings clearly indicate that the extension of penumbra near the geometrical edge of a split beam is considerably less than that of an open beam of the same field size. Consequently when two adjacent fields are used, the overdose at and near the junction plane is reduced greatly by the split beam. For head and neck tumors the split beam technique gives a much better dose distribution than any other conventional treatment techniques.

Evaluation of computed tomography numbers for treatment planning of lung cancer

Computerized tomography numbers (CTN) were evaluated in 32 computerized tomography scans performed on patients with carcinoma of the lung, with the aim of evaluating CTN in normal (lung, blood, muscle, etc) and pathologic tissues (tumor, atelectasis, effusion, post-radiation fibrosis). Our main findings are: 1. Large individual CTN variations are encountered in both normal and pathologic tissues, above and below mean values. Hence, absolute numbers are meaningless. Measurements of any abnormal intrathoracic structure should be compared in relation to normal tissue CTN values in the same scan. 2. Tumor and complete atelectasis have CTN basically similar to soft tissue. Hence, these numbers are not useful for differential diagnosis. 3. Effusions usually have lower CTN and can be distinguished from previous situations. 4. Dosimetry based on uniform lung density assumptions (i.e., 300 mg/cm3) might produce substantial dose errors as lung CTN exhibit very large variations indicating densities well above and below this value. 5. Preliminary information indicates that partial atelectasis and incipient post-radiation fibrosis can have very low CTN. Hence, they can be differentiated from solid tumors in certain cases, and help in differential diagnosis of post radiation recurrence within the radiotherapy field versus fibrosis.

Advantages and limitations of computed tomography scans for treatment planning of lung cancer

Forty-five Chest computed tomography (CT) scans performed on patients with lung carcinoma (LC) were evaluated in an attempt to understand the pattern of intrathoracic tumor spread and the advantages and limitations this technique offers for treatment planning when compared to planning done by conventional X rays. The following findings can help treatment planning. (1) When regular X rays do not show tumor location (i.e., hemithorax opacification), CT scan will show it in 68% of patients. If regular X rays show a well localized mass, unsuspected tumor extensions were disclosed in 78% of these patients. Hence, CT scans should be done in all LC patients prior to treatment planning; (2) Mediastinal masses frequently spread anteriorly toward the sternum and posteriorly around the vertebral bodies toward the cord and costal pleura. This should be considered for radiotherapy boost techniques; (3) Lung masses spread in one third of cases toward the lateral costal pleura. Thus, the usual 1-2cm of safety margin around the LC are not sufficient in some cases; (4) Tumor size can appear much smaller in regular X rays than in CT scans. Hence, CT scans are necessary for accurate staging and evaluation of tumor response. Some CT scan limitations are: (1) Atelectasis blends with tumor in approximately half of the patients, thus obscuring tumor boundaries; (2) CT numbers and contrast enhancement did not help to differentiate between these two structures; and (3) Limited definition of CT scan prevents investigation of suspected microscopic spread around tumor masses.