Stereotactic body radiotherapy of central lung tumours using a 1.5 T MR-linac: First clinical experiences.

Background: MRI-guidance may aid better discrimination between Organs at Risk (OARs) and target volumes in proximity of the mediastinum. We report the first clinical experiences with Stereotactic Body Radiotherapy (SBRT) of (ultra)central lung tumours on a 1.5 T MR-linac. Materials and Methods: Patients with an (ultra)central lung tumour were selected for MR-linac based SBRT treatment. A T2-weighted 3D sequence MRI acquired during free breathing was used for daily plan adaption. Prior to each fraction, contours of Internal Target Volume (ITV) and OARs were deformably propagated and amended by a radiation oncologist. Inter-fractional changes in volumes and coverage of target volumes as well as doses in OARs were evaluated in offline and online treatment plans. Results: Ten patients were treated and completed 60 Gy in 8 or 12 fractions. In total 104 fractions were delivered. The median time in the treatment room was 41 min with a median beam-on time of 8.9 min. No grade ≥3 acute toxicity was observed. In two patients, the ITV significantly decreased during treatment (58 % and 37 %, respectively) due to tumour shrinkage. In the other patients, 81 % of online ITVs were within ±15 % of the volume of fraction 1. Comparison with the pre-treatment plan showed that ITV coverage of the online plan was similar in 52 % and improved in 34 % of cases. Adaptation to meet OAR constraints, led to decreased ITV coverage in 14 %. Conclusions: We describe the workflow for MR-guided Radiotherapy and the feasibility of using 1.5 T MR-linac for SBRT of (ultra) central lung tumours.

[Neurological symptoms as the first sign of prostate carcinoma]. / Neurologische symptomen als eerste uiting van een prostaatcarcinoom.

Three male patients aged 82, 56 and 60 years presented with cognitive impairment and hemiparesis, weakness of the tongue and facial muscles, and pain and weakness of the left arm, respectively. They were found to have carcinoma of the prostate with cerebral, skull and cervical spine metastases. They were treated with hormonal therapy and local radiotherapy for bone metastases. The first patient died within 2 weeks, the second after 1.5 year, and the third was still alive after 6 years. The diagnostic work-up in men with unexplained neurological symptoms should probably include a rectal exam and assessment of prostate-specific antigen.

Analysis of local recurrence after breast conservative treatment for invasive breast cancer: a single institution cohort.

In a group of 900 patients treated for carcinoma of the breast, we evaluated patient-, tumour- and treatment-related parameters, predicting the success or failure of conservative treatment for invasive breast cancer. Thirty-one patients developed local recurrences which were detected within 0.1-12.1 years after treatment of the primary tumour (with a median of 6.2 years), providing a risk of 2% at 5 years and 9% at 10 years. The locally recurrent tumours and their original primary tumours of 28 patients could be retrieved from the pathology laboratory archives. These 28 tumours of the recurrence group (RG) were matched with tumours without local recurrence, the non-recurrence group, for age at time of diagnosis, duration of follow-up and T- and N-stage. The tumours were studied for type and grade of invasive tumour including the in situ component and involvement of surgical margins. In addition, the expression of cell-cycle proteins, p53, Ki-67 (MIB-1) and BCL-1, as well as HER-2/ neu oncoprotein, estrogen and progesterone receptor were investigated. We found a mean age at diagnosis for the RG of 50 years, and the mean age at time of diagnosis for the whole group of 900 patients was 56 years (p=0.003). Thirty-nine percent of the RG had a positive surgical margin, which was the case for only 18% in the control group (p=0.09). The presence of the in situ component was also correlated with increased local recurrence (p=0.022). Furthermore, local recurrence was also associated with a significantly increased occurrence of distant metastases (p=0.001). We conclude that breast conservative treatment is safe with a low local recurrence rate.

The influence of pre-operative radiotherapy on the expression of p53 and adhesion molecules: correlation with treatment results in patients with squamous cell carcinoma or adenocarcinoma.

E-cadherin and the catenins are responsible for inter-cellular adhesion in epithelial tissues. E-cadherin and/or catenin expression is often altered in malignancies, leading to increased invasiveness and metastatic activity of tumour cells. Intact adhesion molecules reduce the risk on distant metastases. This is confirmed by studies mostly performed on surgical series, correlating e-cadherin expression in tumours with prognosis and treatment outcome. It has become more apparent that anti-cancer treatment by itself can also affect the expression of adhesion molecules. We therefore suggest that the prognostic value of e-cadherin expression may depend on the treatment modality and the sequence of therapies administered for malignant tumours. We used paraffin embedded specimens from patients with rectal tumours and patients with laryngeal tumours treated by short course radiotherapy before definitive surgery. Expression of p53, e-cadherin, and beta-catenin was determined in pre-radiotherapy biopsies and in the surgical specimens. Material was available from 37 patients. We found no correlation between the expression of p53, e-cadherin or beta-catenin and pre-treatment parameters. Mutated p53 in pre-radiation biopsy correlated with increased occurrence of distant metastases and there was an unexpected trend for abnormal e-cadherin expression to correlate with reduced metastases. The prognostic value of p53 no longer existed after examination of the surgical specimens (post-radiotherapy). There was a trend for e-cadherin to reverse from abnormal to normal expression in laryngeal squamous cell carcinomas after radiotherapy, in 5/7 cases it was accompanied with p53 conversion from positive to negative expression. Based on this study it is suggested that the predictive value of the e-cadherin expression for the occurrence of distant metastases in tumours treated by radiotherapy before surgery may be different from that found in tumours treated by surgery only. This may be related to the influence of radiotherapy on e-cadherin expression, especially in squamous cell carcinomas. Alteration in p53 expression was of predictive value only in pre-treatment biopsies and the beta-catenin status did not correlate with treatment outcome in this series.

P53 and radiotherapy for oesophageal carcinoma: A comparison between 4 different antibodies.

Wild-type p53 protein plays an important role in the cellular response to ionising radiation and other DNA damaging agents and is mutated in many human tumours. Immunohistochemistry is a rapid method to detect elevated protein levels. The p53 status in a group of patients treated by radiotherapy exclusively for oesophagus carcinoma was examined and correlated with pre-treatment parameters and treatment outcome with regard to overall survival, local recurrence-free survival and distant metastases-free survival. Four different antibodies were used to evaluate their predictive power to detect p53 expression. Immunostaining for p53 protein with 4 different antibodies was performed on paraffin-embedded specimens from 69 patients with adenocarcinoma and squamous cell carcinoma of the oesophagus. All patients were treated with radiotherapy exclusively, consisting of external irradiation combined with intraluminal brachytherapy. Detection of p53 using the antibody (DO7) was significantly correlated with overall survival and distant metastases-free survival. For local recurrence-free survival no statistical significance was reached. The use of the other 3 antibodies all showed the same trend with regard to distant metastases, however statistical significance was not reached. The use of multiple antibodies did not increase the predictive value of DO7. Both for survival and metastases-free survival the use of DO7 alone was sufficient as a significant prognostic factor. We conclude that in this series, only the use of DO7 was correlated with prognosis in oesophagus carcinoma treated by radiotherapy only and that addition of 3 antibodies did not improve the predictive power.

The influence of the oncogene N-ras on cell cycle delay in a human melanoma cell line with reduced radioresistance.

In a previous study we found that transfection of a human melanoma cell line with the oncogene N-ras led to increased radiosensitivity as measured by clonogenic assays. Since a shift in radiosensitivity is often correlated with altered G2/M delay, we investigated whether this was also the case in this oncogene containing melanoma cell line (IGRras). A human melanoma cell line, stably transfected with mutated N-ras, and its parental cell line transfected with the neomycin phosphotransferase gene only (IGRneo), were irradiated with 5 Gy and cell cycle distribution was measured at hourly time intervals by DNA staining with propidium iodide. Next, the effect of ionising radiation on the duration of the S-phase was determined by pulse labelling cells with BrdUrd before irradiation. Both cell lines showed a radiation induced G2/M delay, which was most prolonged for the ras transfected cell line. After 5 Gy, the S-phase duration was unaltered, although the shape of the relative movement (RM) curves was slightly different. No G1 delay was observed in either cell line. Ras transfection in a melanoma cell line leads to prolonged G2/M delay after radiotherapy. This prolongation is associated with increased radiosensitivity and not with radioresistance. These data throw doubt on the use of oncogene expression or G2/M delay as predictors of radiosensitivity.

The effect of a single fraction compared to multiple fractions on painful bone metastases: a global analysis of the Dutch Bone Metastasis Study.

PURPOSE: To answer the question whether a single fraction of radiotherapy that is considered more convenient to the patient is as effective as a dose of multiple fractions for palliation of painful bone metastases. PATIENTS: 1171 patients were randomised to receive either 8 Gy x 1 (n = 585) or 4 Gy x 6 (n = 586). The primary tumour was in the breast in 39% of the patients, in the prostate in 23%, in the lung in 25% and in other locations in 13%. Bone metastases were located in the spine (30%), pelvis (36%), femur (10%), ribs (8%), humerus (6%) and other sites (10%). METHOD: Questionnaires were mailed to collect information on pain, analgesics consumption, quality of life and side effects during treatment. The main endpoint was pain measured on a pain scale from 0 (no pain at all) to 10 (worst imaginable pain). Costs per treatment schedule were estimated. RESULTS: On average, patients participated in the study for 4 months. Median survival was 7 months. Response was defined as a decrease of at least two points as compared to the initial pain score. The difference in response between the two treatment groups proved not significant and stayed well within the margin of 10%. Overall, 71% experienced a response at some time during the first year. An analysis of repeated measures confirmed that the two treatment schedules were equivalent in terms of palliation. With regard to pain medication, quality of life and side effects no differences between the two treatment groups were found. The total number of retreatments was 188 (16%). This number was 147 (25%) in the 8 Gy x 1 irradiation group and 41 (7%) in the 4 Gy x 6 group. It was shown that the level of pain was an important reason to retreat. There were also indications that doctors were more willing to retreat patients in the single fraction group because time to retreatment was substantially shorter in this group and the preceding pain score was lower. Unexpectedly, more pathological fractures were observed in the single fraction group, but the absolute percentage was low. In a cost-analysis, the costs of the 4 Gy x 6 and the 8 Gy x 1 treatment schedules were calculated at 2305 and 1734 Euro respectively. Including the costs of retreatment reduced this 25% cost difference to only 8%. The saving of radiotherapy capacity, however, was considered the major economic advantage of the single dose schedule. CONCLUSION: The global analysis of the Dutch study indicates the equality of a single fraction as compared to a 6 fraction treatment in patients with painful bone metastases provided that 4 times more retreatments are accepted in the single dose group. This equality is also shown in long term survivors. A more detailed analysis of the study is in progress.

E-cadherin expression in oesophageal carcinoma treated with high-dose radiotherapy; correlation with pretreatment parameters and treatment outcome.

BACKGROUND AND PURPOSE: E-cadherin plays an important role in the cell-cell contact of normal epithelium. Loss of E-cadherin expression may be related to tumour invasiveness and metastatic potential. In a group of patients treated for oesophageal carcinoma by radiotherapy only, we found that immunohistochemically detected p53 expression correlated with reduced survival, mainly because of the occurrence of distant metastases. We questioned whether, in this group of patients, E-cadherin expression was concomitantly altered and served as a predictive factor for the development of distant metastases. MATERIALS AND METHODS: Immunostaining for E-cadherin was performed on paraffin- embedded biopsy specimens from patients with adenocarcinoma and squamous cell carcinoma of the oesophagus. E-cadherin status and its correlation with regard to pretreatment parameters and treatment outcome were determined. RESULTS: An aberrant staining pattern of E-cadherin did not correlate with any of the pretreatment parameters. In a univariate analysis, a significantly reduced metastatic potential was found for tumours that had an aberrant cellular staining pattern for E-cadherin, which was strongest for squamous cell carcinomas. However, in a multivariate analysis only p53 status correlated significantly with the occurrence of distant metastases. CONCLUSION: Although, in univariate analysis, aberrant E-cadherin expression served as a better, rather than a worse prognostic factor, p53 status remained the only significant parameter in multivariate analysis, in this group of patients with oesophageal carcinoma. No relationship between p53 status and E-cadherin expression was found.

Pulsed-dose-rate and low-dose-rate brachytherapy: comparison of sparing effects in cells of a radiosensitive and a radioresistant cell line.

Pulsed-dose-rate regimens are an attractive alternative to continuous low-dose-rate brachytherapy. However, apart from data obtained from modeling, only a few in vitro results are available for comparing the biological effectiveness of both modalities. Cells of two human cell lines with survival fractions of 80% (RT112) and 10% (HX142) after a single dose of 2 Gy and with different halftimes for split-dose recovery and low-dose recovery were used. The cells were irradiated with a continuous low dose rate (80 cGy per hour) or with pulsed dose rate. Two different pulsed dose rates were tested: 4.25 Gy/h and 63 Gy/h. The effects of dose per pulse and the length of the interval between the pulses were investigated while keeping the overall treatment time constant. Survival after low-dose-rate irradiation was indistinguishable from that after pulses of 4.25 Gy/h in cells of both cell lines. Survival decreased with increasing dose per pulse. When the dose rate during the pulses was increased, survival decreased even further. This effect was most pronounced for the radiosensitive HX142 cells. In clinical pulsed-dose-rate brachytherapy, iridium sources move stepwise through the implant and deliver pulses at a high dose rate locally. These high-dose-rate pulses produce greater biological effectiveness compared to continuous low dose rate; this should be taken into account.

Radiotherapy for oesophagus carcinoma: the impact of p53 on treatment outcome.

BACKGROUND AND PURPOSE: Wildtype p53 protein plays an important role in the cellular response to ionizing radiation and other DNA damaging agents and is mutated in many human tumours. We evaluated the relationship of the immunohistochemically determined p53 protein status and the disease control with radiotherapy alone for carcinoma of the oesophagus. MATERIALS AND METHODS: Immunostaining for p53 protein was performed on paraffin-embedded specimens from 69 patients with adeno- and squamous cell carcinoma of the oesophagus. All patients were treated by radiotherapy exclusively, consisting of a combination of external irradiation and intraluminal brachytherapy, using two different dose levels. RESULTS: Fifty-four percent (37/69) of the tumours showed overexpression of the p53 protein. No difference in pre-treatment parameters for p53-positive and p53-negative cases was detected. In multivariate analysis p53 was significantly associated with overall survival (OS) next to weight loss, tumour stage and N-stage. For metastatic-free survival (MFS) p53 status proved to be the sole independent prognostic factor. The influence of p53 on local recurrence-free survival (LRFS), however, was not as strong as on OS and MFS. CONCLUSIONS: Immunohistochemically detected overexpression of mutated p53 protein in oesophagus carcinoma was an independent prognostic factor in a group of patients treated with radiotherapy alone.

[Three scenarios of labor supply for the next 25 years]. / Drie scenario's van het arbeidsaanbod voor de komende 25 jaar.

PIP: "The future development of labour supply [in the Netherlands] depends on two factors: (1) demographic changes: population by age, sex, level of educational attainment and ethnicity; (2) changes in labour force participation rates. Three scenarios of labour supply in the period 1995-2020 are based on alternative assumptions on future changes in these factors. The main trend is the increase of labour force participation of women. Ageing has a negative impact on labour supply, as the labour force participation rates of the elder age groups are relatively low. The increase of the level of educational attainment has a moderate positive impact." (EXCERPT)^ieng

The influence of the oncogenes NRAS and MYC on the radiation sensitivity of cells of a human melanoma cell line.

Activation of certain oncogenes may alter the sensitivity of cells to ionizing radiation. We studied the effect of oncogene activation on the radiation sensitivity of cells of a human melanoma cell line. The cell line IGR39D was transfected with the MYC oncogene, the proto-oncogene NRAS, NRAS activated by a point mutation (61-arginine) or a combination of mutated NRAS and MYC. Single-dose experiments showed a decreased survival after transfection with MYC, wild-type NRAS or mutated NRAS. Co-transfection with MYC and mutated NRAS decreased survival up to 4 Gy, whereas at higher doses no shift in radiosensitivity was seen. Flow cytometry data indicated that differences in radiosensitivity could be explained at least in part by a difference in the distribution of cells in the phases of the cell cycle. After transfection of cells with either NRAS or MYC, the number of cells in G1 phase decreased with a concomitant increase of cells in the G2/M phase. When the cell line transfected with activated NRAS was manipulated so that the distribution of the cells in the phases of the cell cycle resembled th at of the parental line at the time of irradiation, the survival of the cells was improved. Similar experiments with the cell line containing MYC did not result in an alteration of the distribution of the cells in the cycle, or the survival after single-dose fractions, suggesting the presence of a distinct mechanism for influencing radiation sensitivity. Both NRAS and MYC transfection decrease the radiation sensitivity of human melanoma cells, but the underlying mechanisms seem different. In conclusion, transfection with NRAS or MYC alone increases radiation sensitivity while transfection of cells containing NRAS with MYC restores resistance at higher doses.

Cell density dependent plating efficiency affects outcome and interpretation of colony forming assays.

BACKGROUND AND PURPOSE: The usefulness of colony forming assays (CFA) has been established for almost 40 years (Puck and Marcus, J.Exp.Med. 103: 653-666, 1956). Although time-consuming and not successful for all cell lines, it is generally considered to be the gold standard of assays for testing the sensitivity of cell lines to ionizing radiation or other cytotoxic agents in vitro. We recently found for several cell lines that the plating efficiencies of both control and irradiated cells is dependent upon the density of cells seeded for colony formation; that is, increasing cell inoculum levels resulted in a non-linear relationship with colony formation, even at relatively low colony numbers. MATERIAL AND METHODS: All data from a human melanoma cell line, transfected with c-myc or N-ras, as well as from normal human diploid fibroblasts, were taken to see how this phenomenon influenced outcome and interpretation of clonogenic assays. Survival was recalculated using all data, or only data with a linear relationship between inoculum level and colony formation. RESULTS: It is found that when data with a non-linear relationship between inoculum level and colony formation are included, survival can be underestimated due to inhibition of colony formation in treated cultures. CONCLUSION: For validity, colony forming assays must be standardized to assure a constant relationship between the cell density and colony forming efficiency. This usually requires a much lower density of colonies than has been typically published for many cell survival studies.

Combined radio-surgical treatment in early invasive cervix carcinoma according to prognostic factors. Experience of the Gustave-Roussy Institute.

In the Gustave-Roussy Institute the standard protocol of limited stages (IB, proximal II) of cervix carcinoma, combines endocavitary brachytherapy (low dose rate) and surgery (BSOH + lymphadenectomy) are eventually followed by external beam irradiation. According to age of patients and to prognostic factors adaptations of this combined treatment are discussed: young patient (40 years) with small tumor, large volume of primary tumor (4 cm), lymphatic node involvement. Analysis of the results in 2 series of patients entirely treated at the Gustave-Roussy Institute: survival, local control, metastases, complications.

Radiation therapy of squamous cell carcinoma of the nasal vestibule.

From 1978 until 1988, 63 consecutive patients with squamous cell carcinoma of the nasal vestibule were treated by radiation therapy. Mean follow-up time was 46 months. Thirty-five patients were classified as having T1N0 tumors, 24 as T2N0; four patients were staged as T1/2N+. Treatment of the primary consisted of external radiation (n = 17), interstitial radiation (n = 37), or external radiation combined with interstitial radiation (n = 9). With respect to the N0 patients, local relapse was found in 3% (1/35) of T1 tumors and in 21% (5/24) of T2 tumors. Three out of six failures were salvaged by surgery. Elective irradiation of both sides of the neck (40 Gy) was performed in 9 T1 and in 16 T2 patients. Two regional failures occurred in the electively irradiated necks, two in the non-irradiated necks. Regarding the T1/2N+ patients, three relapsed locally and/or regionally, and one remains NED. For all 63 patients, a 5-year corrected survival of 90%, a relapse-free survival of 80%, and an overall survival of 65% were observed. In summary, for optimal local control and cosmesis we feel that for T1,2 N0 tumor stages a dose of 60 Gy for T1 and 70 Gy for T2 tumors is adequate treatment. The primary tumor is irradiated preferentially in our view, by means of interstitial techniques; furthermore, our data do not support the use of elective neck RT. Although patients rarely present with lymph node metastasis (6%), the prognosis of T1,2 N+ patients remains grim and more aggressive (surgical) treatment might be needed for this category.

Reirradiation of recurrent tumors in the head and neck.

From 1971 to 1980, 55 patients were reirradiated in the Dr. Daniel den Hoed Kliniek for a recurrent cancer in the head and neck. For all patients considered, the primary treatment consisted of full course radiation therapy (RT) only; the recurrent tumors were irradiated with external and/or interstitial radiation therapy. In some of these patients, the reirradiation was combined with surgery and/or chemotherapy. A poor overall survival was found, i.e., after 5 years only 20% of the patients are still alive. Although the patients with a recurrent tumor of the nasopharynx seem to fare slightly better, no statistically significant difference was found for the different sites in the head and neck. A trend towards a somewhat better survival was observed for subsets of patients for whom either the reirradiation was combined with surgery or for whom the time period elapsed between the primary treatment and the initiation of the second irradiation was more than 12 months. Moreover, best local control was seen in recurrent tumors reirradiated by high doses of RT; i.e., with 50 Gy or more, a local control rate of 48% was obtained. Future treatment strategies towards a better local control and survival are discussed.