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Biomedical subjects

L J Peters

Publications and source records attributed to L J Peters.

At least 127 records · Page 7Linked to original sources
PubMed1990

T2 glottic cancer. Recurrence, salvage, and survival after definitive radiotherapy.

The records of all patients with T2, NO squamous cell carcinoma of the true vocal cords treated with definitive radiotherapy at The University of Texas M. D. Anderson Cancer Center between 1970 and 1985 were analyzed to investigate treatment outcome, prognostic factors associated with tumor recurrence, and the potential impact of improved initial treatment on patient survival. There were 114 patients (male to female ratio, 13:1) with a median age of 62 years at presentation. All were treated with external beam irradiation to a modal dose of 70 Gy in 35 fractions over 7 weeks. The median field size was 25 cm2 and no elective treatment to the neck was routinely given. The crude recurrence rate after definitive radiotherapy was 32%. Of the 37 local regional failures, 32 were in the larynx only, 3 in the neck, and 2 in both the larynx and the neck. All patients who had recurrence after radiotherapy underwent salvage procedures, which increased the ultimate control rate above the clavicles to 94%. Overall and disease-specific survival rates at 5 years were 69% and 92%, respectively. Fifty patients died: 7 of laryngeal cancer, 2 of complications of salvage surgery, 13 of unrelated second cancers, and 28 of other intercurrent disease. The prospects for improved survival through more effective initial treatment of this stage of glottic cancer are therefore very limited. Significant complications of radiotherapy occurred in only 4 patients (3.5%), and overall, 74% of patients retained a functional larynx. Analysis of a wide variety of patient-, tumor-, and treatment-related variables failed to identify any statistically significant prognostic factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

The ESTRO Regaud lecture. Inherent radiosensitivity of tumor and normal tissue cells as a predictor of human tumor response.

This lecture reviews the history and current status of attempts to correlate the outcome of radiation therapy with estimates of tumor cell radiosensitivity, made by either histologic assessment of tumors irradiated in vivo or by assays for the survival of tumor cells irradiated in vitro. Genetically determined variability in the radiosensitivity of normal tissue cells from different individuals is also discussed in terms of its effect on the determination of "tolerance" doses and the possible correlation between tumor cell and normal tissue cell radiosensitivity in a given patient. It is concluded that measurement of both tumor cell and normal tissue cell radiosensitivities, along with other radiobiologically-based assays, will improve our ability to predict treatment outcome and provide the basis for further therapeutic advances in radiation oncology.

Cell Survival↗
PubMed1990

Nasopharyngeal carcinoma in the young: a combined M.D. Anderson and Stanford experience.

From 1956 to 1988, 57 children and young adults (age 4-21 years) with a diagnosis of nasopharyngeal carcinoma were treated at The University of Texas M.D. Anderson Cancer Center (42 patients) and Stanford University Medical Center (15 patients). The male to female ratio was 2:1. Forty-three patients had lymphoepithelioma, seven had undifferentiated neoplasms, and seven had squamous cell carcinoma. Two patients had Stage III disease and the remainder had Stage IV disease at the time of presentation. All patients were treated with primary radiotherapy, and 14 patients also had chemotherapy with combinations of the following drugs: dactinomycin, doxorubicin, bleomycin, cisplatin, cyclophosphamide, fluorouracil, methotrexate, and vincristine. Twenty-six patients are alive 6 to 178 months from the first day of treatment (median 93 months). The 5- and 10-year actuarial survival rates are 51% and 36%, respectively, and the corresponding disease specific survival rates were 51% and 51%. There were no recurrences after 42 months. The patterns of failure were as follows: distant metastasis only, 21 patients; locoregional metastasis only, 1; both, 5. Distant metastases most commonly occurred in bones, lungs, liver, and mediastinal lymph nodes. Chronic treatment-related morbidity was encountered in a significant number of long term survivors. Trends in the data not reaching statistical significance suggest a more favorable prognosis for a) females, b) patients less than or equal to 15 years of age, c) lymphoepithelioma or undifferentiated histologies, d) stages T3-4 NO-1 vs T1-2 N2-3 vs T3-4 N2-3, e) primary tumor dose greater than or equal to 65 Gy and f) patients who received chemotherapy.

Adolescent↗
PubMed1990

Radiation myelopathy in primates treated with conventional fractionation.

A rhesus monkey model was used to assay the radiation tolerance of the spinal cord to 60Co radiation given in 2.2 Gy fractions. The D50 was found to be 76.1 Gy (SEM = 1.9 Gy); the estimated doses for 1% and 0.1% myelopathy were 59.1 +/- 5.5 Gy and 52.1 +/- 7.1 Gy, respectively. The latent period ranged from 5 to 20 months and decreased with increasing dose. All symptomatic animals had white-matter parenchymal lesions involving major motor tracts, and most also had vascular lesions in the white matter. Spinal cords of asymptomatic animals had either no histopathologic changes or small white-matter lesions that did not involve motor tracts.

Animals↗
PubMed1990

Cellular radiosensitivity of primary head and neck squamous cell carcinomas and local tumor control.

The low dose survival parameters of human tumor cell lines have been shown to correlate with the perceived clinical radiosensitivity of different tumor histologic types. This conclusion has been generated from the analysis of a large number of cell lines and has, therefore, served as the basis for attempts to develop predictive assays of tumor radiocurability. In this study, the tumors from 72 patients with head and neck squamous cell carcinoma have been grown in an adhesive tumor cell assay system and their sensitivity to radiation has been measured. All patients in this study were treated with post-operative radiotherapy, the surgical margins were negative, and any patient that had received chemotherapy was excluded. The average S2 (survival at 2.0 Gy) value of the 72 cultures was 0.33, with the values ranging from 0.11 to 0.91. All patients were evaluated for local tumor control. They have been followed for about 1 year and continued follow-up is still in progress. The average survival at 2.0 Gy of cultures derived from the 12 patients that have had recurrences so far is slightly higher (0.40) than that from those who appear so far to have local tumor control (0.30). Although the general trend is that recurrent tumors yield primary cultures that are slightly more resistant, the difference is not statistically significant.

Carcinoma, Squamous Cell↗
PubMed1990

Primary radiotherapy in the treatment of stage I and II oral tongue cancers: importance of the proportion of therapy delivered with interstitial therapy.

From January 1963 through December 1979, 103 patients with Stage T1N0 and T2N0 squamous cell carcinomas of the oral tongue were treated with definitive radiotherapy. The primary was Stage T1 in 18 patients and T2 in 85 patients. Therapy to the primary consisted of interstitial therapy only in 18 patients, 16-37 Gy in 2.4-4.0 Gy fractions followed by interstitial therapy to doses of 38-55 Gy in 31 patients, external therapy of 40-50 Gy with interstitial therapy of 20-40 Gy in 46 patients, and external beam only to doses of 45-82 Gy in 8 patients. Follow-up ranged from 2 to 290 months (median 159 months). Five of the 8 patients treated with external therapy alone and 6 of the 18 patients treated with interstitial therapy failed at the primary site. In those patients treated with a combination of external and interstitial therapy the 2-year local control rate was 92% for patients treated with external therapy to doses of less than 40 Gy combined with a moderately high dose of brachytherapy, compared with 65% for patients who received external therapy to doses of greater than or equal to 40 Gy with lower brachytherapy doses (p = .01). Conversely the risk of failure in the neck was directly related to the dose delivered by external beam therapy. In field recurrence occurred in 44% of patients receiving no therapy to the neck. 27% in those receiving less than 40 Gy, and 11% in those patients with neck treatment to greater than or equal to 40 Gy. Eleven of 87 (13%) of patients who were at risk for complications for greater than or equal to 24 months developed severe complications; severe complications were more likely to occur in the group who received most of their therapy with external beam irradiation. These data show that a high dose of interstitial therapy is necessary to secure optimum local control of early primary tongue cancer. Because of the high frequency of moderate to severe late complications in this series we have adopted a policy of initial surgery for most oral tongue cancers with postoperative radiotherapy if indicated by pathological features predictive of a high rate of local-regional failure.

Adult↗
PubMed1990

Concomitant boost radiotherapy schedules in the treatment of carcinoma of the oropharynx and nasopharynx.

Concomitant boost schedules are characterized by delivering the boost (10-12 fractions) as second daily treatments during rather than following the basic wide field irradiations. This results in shortening the overall time to administer 69-72 Gy from 7 1/2-8 weeks to 6 weeks, which we hoped would improve the tumor control rate by reducing the opportunity for tumor clonogens to regenerate during treatment. From August 1985 to August 1988, 79 patients with T2-4 carcinomas of the oropharynx (72 patients) or nasopharynx (7 patients) were treated according to 1 of the 3 variants of the concomitant boost technique. The median age of patients was 60 years (range: 19-84 years) and the male-to-female ratio was 2.6. The overall 2-year actuarial primary and nodal control rates by radiotherapy alone were 74% and 76%, respectively. The ultimate 2-year control rates after surgical salvage were 82% and 84%, respectively. If the boost given during the last 2-2 1/2 weeks of basic treatment, a slightly better primary control rate (p = 0.11) resulted than if the boost was delivered during the first 2-2 1/2 weeks or twice a week throughout the basic treatment. The 2-year actuarial primary control rate of the 13 patients receiving induction chemotherapy prior to radiotherapy was significantly lower than that of patients treated with radiation only (81% vs 34%, p = 0.01), but this could be partly attributed to a more advanced stage in the chemotherapy group. The acute mucosal reactions were, as expected, more severe than those observed with conventional fractionation. Fifty patients developed confluent mucositis covering more than half of the boost area. Such reactions lasted for more than 6 weeks in seven patients. Late complications, however, so far observed, have been few. Three patients experienced chronic mucosal tenderness, 1 chronic mucosal ulceration, 2 transient bone exposure, and 1 carotid rupture following salvage surgery. The results so far appear to be better than the outcome of conventional radiotherapy. Its real value will be determined in a prospective randomized study.

Adult↗
PubMed1990

The essential role of radiation therapy in securing locoregional control of Merkel cell carcinoma.

Between 1966 and 1987, 54 patients with non-disseminated Merkel cell carcinoma (MCC) were treated with curative intent at the University of Texas M. D. Anderson Cancer Center. The primary tumor site was in the head and neck in 38 patients. The majority of the patients (57%) were referred with locoregionally recurrent disease. For the whole group, survival was 30% after 5 years. Patients who presented with nodal involvement had a median survival of 13 months compared with 40 months for node-negative patients (p less than .04). Only 4/37 patients treated initially by surgery alone were locoregionally controlled, with a median time to recurrence of 4.9 months. Salvage with radiation therapy was attempted in 18 patients (after additional surgery in 14), but was successful in only four. The predominant failure pattern in this subgroup was distant metastases, occurring as a component of initial recurrence in 12/18 patients. Prior to 1982, the philosophy of initial therapy was to give postoperative irradiation only to patients with large primaries or nodal involvement. Subsequently, postoperative radiotherapy has been recommended routinely, and all five patients treated with this approach remain disease-free. In total, 31 patients (including 10 patients with gross disease) were irradiated at M. D. Anderson; only one developed an in-field locoregional recurrence as an initial site of failure. However, three marginal recurrences occurred. The median dose to the primary tumor, first echelon nodes, and supraclavicular nodes was 60, 51, and 50 Gy, respectively. Our current recommendation for initial treatment is excision of the primary tumor followed by irradiation with generous fields to include the primary tumor site and draining regional lymphatics to doses of 46-50 Gy in 2 Gy fractions. For gross unresected disease, 56-60 Gy is recommended. The role of adjuvant systemic therapy remains to be defined.

Adult↗
PubMed1990

Treatment selection for carcinoma of the base of the tongue.

Between 1974 and 1984, 173 patients were treated for squamous cell carcinoma of the tongue base. Fifty-four patients had T1 or T2 primaries, while 115 patients had T3 or T4 tumors (4 were not staged). Lymph node metastasis was present in 120 patients. Early primary tumors treated with surgery or radiotherapy had a control rate of 83% (5 of 6 tumors) and 89% (40 of 45 tumors), respectively. For advanced primary tumors, definitive radiotherapy produced a local control rate of 55% (42 of 76 tumors), compared with 79% (23 of 29 tumors) for surgery and postoperative radiotherapy. If primary control was obtained, the regional failure rate was less than 10%. Tumor growth patterns were predictive of the response to radiotherapy. The primary control rate at 2 years for 21 patients with exophytic tumors was 84% as opposed to 58% for 62 patients with ulcerative-infiltrative tumors (p = 0.04). Radiotherapy is effective for early stage or exophytic tumors, whereas for advanced or deeply invasive tumors combined therapy enhances local control.

Adult↗
PubMed1990

[Predictive tests of radiocurability: towards a custom-made radiotherapy?].

Up to now, radiation oncologists had at their disposal only a number of well-known histological and clinical factors in order to define the optimal dose which should be delivered to a given tumor. Recently, radibiological studies have suggested additional parameters which may play a major role in tumor radiocurability. These parameters are: the number of clonogenic cells, intrinsic radiosensitivity, hypoxia and proliferation kinetics. "Predictive" tests are being developed and evaluated for each of these parameters. The more advanced studies deal with intrinsic radiosensitivity; preliminary data show impressive variations in radiosensitivity within groups of clinically "homogeneous" tumors. Should these tests prove to be reliably predictive of radiocurability, it will be possible, in the near future, to propose to any given patient a "custom-made radiotherapy" adapted to the precise features of his or her tumor.

Animals↗
PubMed1989

Tumor bed effect-induced reduction of tumor radiocurability through the increase in hypoxic cell fraction.

Two murine tumors, designated FSA and SA-NH, that exhibit strong tumor bed effect (TBE), were found to be less radiocurable if they grew in the preirradiated s.c. tissue. Tumors were transplanted into the right thighs irradiated with 30 Gy one day earlier, and were irradiated when they grew to 6 mm. The TBE-caused reduction in tumor radiocurability was manifested by the increase in TCD50 values. Tumor irradiation under hypoxic conditions increased TCD50 values less, and the hypoxic cell radiosensitizer misonidazole reduced TCD50 values more, when tumors grew in preirradiated than when they grew in unirradiated legs. This implies that TBE-induced increase in TCD50 was due to increase in hypoxic fraction of tumor cells. For 6 mm SA-NH tumor the estimated increase in hypoxic cell fraction was from the control value of 3% to 12%. Thus, TBE causes the reduction in tumor radiocurability through the increase in hypoxic fraction of tumor cells.

Aerobiosis↗
PubMed1989

Hyperfractionated radiotherapy in the treatment of squamous cell carcinomas of the supraglottic larynx.

From January 1984 through December 1987, 41 patients with squamous cell carcinomas of the supraglottic larynx were treated with hyperfractionated radiotherapy at The University of Texas M. D. Anderson Cancer Center. Two patients had T1 primary tumors, 23 had T2, 15 had T3, and 1 had T4; 29 patients had no clinical evidence of nodal disease in the neck, 4 had N1, 5 had N2, and 3 had N3. Radiotherapy was delivered in 120 cGy fractions twice per day, with at least 4 hr between treatments. Total doses ranged from 7200 to 7900 cGy (median, 7680 cGy). Three patients had planned neck dissections before or after radiotherapy, and three patients with fixed vocal cord lesions were treated with preradiation chemotherapy. At the time of analysis, median follow-up was 22 months. Four patients have had failures at the primary tumor site. There has been one recurrence in the neck in a patient who also had a recurrence at the primary site. Three of the four patients with recurrences have been successfully treated with salvage surgery. Exclusive of surgical salvage, the actuarial disease-free local control rates above the clavicles in the 38 patients with T2 and T3 cancers were 96% at 1 year and 87% at 2 years. In comparison, the rates were 82% and 76% for a group of 98 patients with T2 and T3 lesions treated at this institution from 1970 to 1981 with 6500-7000 cGy given in 200 cGy fraction per day. As predicted, acute reactions were more severe but late complications were not increased in patients who received hyperfractionated radiotherapy compared with those treated by conventionally fractionated therapy. Only two patients have developed severe late complications one of whom required laryngectomy. Hyperfractionated radiotherapy appears to provide improved local control with a similar incidence of late complications when compared with conventionally fractionated therapy. To further improve the therapeutic ratio, our current protocol has been amended by reducing the large field dose per fraction to 110 cGy (with a 2 day protraction of overall time) and requiring a minimum interfraction interval of 6 hr.

Adult↗
PubMed1989

Definitive radiotherapy for squamous cell carcinoma of the tonsillar fossa.

Between July 1968 and December 1983, 150 patients with previously untreated squamous cell carcinomas of the tonsillar fossa received megavoltage external beam irradiation with curative intent at U.T.M.D. Anderson Cancer Center. These patients were treated following a series of patients who had received radiotherapy between 1954 and May 1968. One hundred and thirty-seven patients were treated with conventional fractionation, the mean doses to the primary being 64.3 Gy, 67.8 Gy, 70.2 Gy, and 72.6 Gy for T1, T2, T3, and T4 lesions respectively. Thirteen patients were treated by altered fractionation schedules, 7 by hyperfractionation, and 6 by a concomitant boost to the primary. Elective bilateral neck irradiation was routine in all patients. A planned neck dissection was performed in 26 patients. The 5-year actuarial overall and disease-specific survival rates were 47% and 70%, respectively. Absolute local control rates with a minimum of 2 years follow-up after irradiation were 94%, 79%, 58%, and 50% for patients with T1, T2, T3, and T4 disease respectively. A total of 37 patients had local treatment failure; in 5 of 18 surgical salvage was successful. Only 4 patients with primary disease control developed failure in the neck and none of those with N0 or N1 disease did so when the primary was controlled. Twelve patients developed transient self-limited bone exposure, 7 developed osteoradionecrosis of the mandible, all requiring surgical resection. Most severe late complications occurred in patients with T3 and T4 lesions whose dose to the primary exceeded 67.5 Gy.

Adult↗
PubMed1989

Radiosensitivity of human head and neck squamous cell carcinomas in primary culture and its potential as a predictive assay of tumor radiocurability.

The intrinsic radiosensitivity of human tumor cell cultures correlates with the clinical radiosensitivity of several different tumor histologies, as evidenced by analyses of low dose parameters of radiation survival curves generated from a large number of cell lines. Such radiosensitivity has therefore served as a basis of attempts to develop predictive assays of tumor radiocurability. In this study, the tumors from 72 patients with head and neck squamous carcinoma have been grown in an adhesive tumor-cell assay system and radiosensitivity (S2: survival at 2.0 Gy) values have been measured. The characteristics of these cultures, such as growth rate, clonogenicity and growth enhancement by epidermal growth factor, do not correlate with S2. The average S2 value of the 72 cultures is 0.33, which is lower than for cultures derived from melanomas and lung adenocarcinomas. Twenty-six patients followed up for at least 15 months have been evaluated for local tumor control. The average S2 value of the seven patients with recurrences in this group is slightly higher (0.43) than that from the other patients (0.30). There is considerable overlap of S2 values in the two groups, and more patients must be evaluated before the groups can be compared statistically.

Carcinoma, Squamous Cell↗
PubMed1989

Fast neutron teletherapy in advanced epidermoid head and neck cancer. A review.

An extensive review of clinical studies employing fast neutron teletherapy for advanced epidermoid carcinomas of the head and neck is presented. Head and neck tumors have represented an excellent study site because of their accessibility to physical examination for measurement of tumor response, and because early neutron beams have had poor depth dose characteristics, making the treatment of more deeply seated tumors technically difficult. A summary of the major trials comparing neutron and mixed-beam (combination neutron and photon) therapy with conventional therapy indicates no conclusive evidence of improvement in local control or survival rates for the experimental arms. Exceptions to this are the Hammersmith experience and the slightly higher lymph node control rates seen in two studies. An evaluation of toxicity indicates that with the new generation of cyclotrons, complication rates may approach parity with those of photon linear accelerators.

Carcinoma, Squamous Cell↗