Advertisement

Lung Cancer pp 75-96 | Cite as

Radiation Therapy in Cancer of the Lung

  • Thomas O’Connor
Part of the Medical Radiology book series (MEDRAD)

Abstract

Technique in any discipline is the acting out of the thinking process. It does not exist isolated from the stream of the general care of a patient with lung cancer; it is not an end in itself. It is a means to an end, either the creation of conditions that will allow for a cure of the patient or the palliation of his symptoms if cure is precluded by the extent of his disease.

Keywords

Lung Cancer Brain Metastasis Vocal Cord Small Cell Carcinoma Spinal Cord Compression 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Abramson N, Cavanaugh PJ (1970) Short-course radiation therapy in carcinoma of the lung, Radiology 96:627–630.PubMedGoogle Scholar
  2. Abramson N, Cavanaugh PJ (1973) Short-course radiation therapy in carcinoma of the lung: a second look, Radiology 108:685–687.PubMedGoogle Scholar
  3. American Cancer Society (1980) Cancer of the lung, CA 39:199–207.Google Scholar
  4. Angell M (1982) The quality of mercy, N Engl J Med 306:98–99.PubMedGoogle Scholar
  5. Baker R (1979) Pleural and pericardial effusions. In: Abeloff Md (ed) Complications of cancer, The Johns Hopkins Univ Press, Baltimore London p 169–184.Google Scholar
  6. Berry RJ, Laing AH, Newman CR, et al (1977) The role of radiotherapy in treatment of inoperable lung cancer, Int J Radiat Oncol Biol Phys 2:433–439.PubMedGoogle Scholar
  7. Bloedorn FG, Cowley RA, Cuccia CA, et al (1961) Combined therapy: irradiation and surgery in the treatment of bronchogenic carcinoma, Am J Roentgenol Radium Ther Nucl Med 85:875–885.Google Scholar
  8. Bloedorn FG, Bowley RA, Cuccia CA, et al (1964) Preoperative irradiation in bronchogenic carcinoma, Am J Roentgenol Radium Ther Nucl Med 92:77–87.PubMedGoogle Scholar
  9. Boag JW, Haybittle JL, Fowler JF, et al (1971) The number of patients required in a clinical trial, Br J Radiol 44:122–125.PubMedGoogle Scholar
  10. Bonarigo BC, Rubin P (1967) Nonunion of pathological fracture after radiation therapy, Radiology 88:889–898.PubMedGoogle Scholar
  11. Borgelt B, Gelber R, Kramer S, et al (1980) The palliation of brain metastases: final results of the first two studies by the radiation therapy oncology group, Int J Radiat Oncol Biol Phys 6: (6): 1–9.PubMedGoogle Scholar
  12. Brashear RE (1978) Editorial: Should asymptomatic patients with inoperable bronchogenic carcinoma receive immediate radiotherapy? No. Am Rev Respir Dis 117:411–414.Google Scholar
  13. Bruckman JE, Blomer WD (1978) Management of spinal cord compression, Semin Oncol 5:135–140.PubMedGoogle Scholar
  14. Budinger JM (1958) Untreated bronchogenic carcinoma. A clinicopathological study of 250 autopsied cases, Cancer 11:106–116.PubMedGoogle Scholar
  15. Butler AR, Leo JS, Lin JP, et al (1979) The value of routine cranial computed tomography in neurologically intact patients with primary carcinoma of the lung, Radiology 131:399–401.PubMedGoogle Scholar
  16. Chapman GS, Kumar D, Redmond J III, et al (1982) Letter to the editor: Upper abdominal CT scanning in staging non-oat cell lung carcinoma, N Engl J Med 307:189.PubMedGoogle Scholar
  17. Choi NC, Grillo HC, Gardiello M, et al (1980) Basis for new stategies in postoperative radiotherapy of bronchogenic carcinoma, Int J Radiat Oncol Biol Phys 6:31–35.PubMedGoogle Scholar
  18. Choi NC, Doucette JA (1981) Improved survival of patients with unresectable non-small cell bronchogenic carcinoma by an innovated high-dose en-bloc radiotherapeutic approach, Cancer 48:101–109.PubMedGoogle Scholar
  19. Choi NC (1982) Editorial: Reassessment of the role of postoperative radiation therapy in resected lung cancer, Int J Radiat Oncol Biol Phys 8:2015–2018.PubMedGoogle Scholar
  20. Chung CK, Stryker JA, O’Neill M Jr, et al (1982) Evaluation of adjuvant postoperative radiotherapy for lung cancer, Int J Radiat Oncol Biol Phys 8:1877–1880PubMedGoogle Scholar
  21. Cohen L (1982) The tissue volume factor in radiation oncology, Int J Radiat Oncol Biol Phys 8:1771–1774.PubMedGoogle Scholar
  22. Cox JD, Petrovich Z, Paig C, et al (1978) Prophylatic cranial irradiation in patients with inoperable carcinoma of the lung. Preliminary report of a cooperative trial, Cancer 42:1135–1140.PubMedGoogle Scholar
  23. Cox JD, Yesner R, Mietlowoki W, et al (1979) Influence of cell type on failure pattern after irradiation for locally advanced carcinoma of the lung, Cancer 44:94–98.PubMedGoogle Scholar
  24. Cox JD, Komaki R, Eierst LR (1980) Irradiation for inoperable carcinoma of the lung and high performance status. JAMA 244:1931–1933.PubMedGoogle Scholar
  25. Coy P, Kennelly GM (1980) The role of curative radiotherapy in the treatment of lung cancer, Cancer 45:698–702.PubMedGoogle Scholar
  26. Deeley TJ (1966) A clinical trial to compare two different tumour dose levels in the treatment of advanced carcinoma of the bronchus, Clin Radiol 17:299–301.PubMedGoogle Scholar
  27. Deeley TJ (1967) The treatment of carcinoma of the bronchus, Br J Radiol 40:801–822.PubMedGoogle Scholar
  28. Dunnick NR, Ihde DC, Johnston-Early A (1979) Abdominal CT in the evaluation of small cell carcinoma of the lung, AJR 133:1085–1088.PubMedGoogle Scholar
  29. Durrant KR, Berry RJ, Ellis F, et al (1971) Comparison of treatment policies in inoperable bronchial carcinoma, Lancet 1:715–719.PubMedGoogle Scholar
  30. Easson EC (1967) The management of Hodgkin’s disease and allied disorders. In: Deeley TJ, Wood CAP (eds) Modern trends in radiotherapy, Butterworths London, p 579.Google Scholar
  31. Editorial (1976) Osteolytic metastases, Lancet 2:1063–1064.Google Scholar
  32. Einhorn L (1983) Reporting on chemotherapy of both small cell and non-small cell lung cancer, The Clin Cancer Let 6(2):4.Google Scholar
  33. Eisert DR, Cox JD, Komaki R (1976) Irradiation for bronchial carcinoma. Reasons for failure. I. Analysis of local control as a function of dose, time, and fractionation, Cancer 37:2665–2670.PubMedGoogle Scholar
  34. Emami B, Melo A, Carter B, et al (1978) Value of computed tomography in radiotherapy of lung cancer, AJR 131:63–67.PubMedGoogle Scholar
  35. Emami B, Munzenrider JE, Lee DJ, et al (1979) Radical radiation therapy for advanced lung cancer, Cancer 44:446–456.PubMedGoogle Scholar
  36. Fajardo LF (1982a) Cardiovascular system. In: Pathology of radiation injury, chap 3, Masson Publishing, USA, p 15–33.Google Scholar
  37. Fajardo LF (1982 b) In: Pathology of radiation injury, chap 16, Masson Publishing, USA, p 220–226.Google Scholar
  38. Feinstein AR (1967a) In: Clinical judgement, Williams and Wilkins Co., Baltimore, p 317.Google Scholar
  39. Feinstein AR (1967 b) A new staging system for cancer and reappraisal of “early” treatment and cure by radical surgery, N Engl J Med 279(14): 747–753.Google Scholar
  40. Fidler IJ, Hart IR (1982) Biological diversity in metastatic neoplasms: origins and implications, Science 217: 998–1003.PubMedGoogle Scholar
  41. Fitzgerald RH, Marks RD, Wallace KM (1981) Chronic radiation myelitis, Radiology 144:609–612.Google Scholar
  42. Foley KM (1979) Pain syndromes in patients with cancer. In: Advanced pain research and therapy, Raven Press, New York.Google Scholar
  43. Fowler JR, Travis EL (1978) The radiation pneumonitis syndrome in half-body radiation therapy, Int J Radiat Oncol Biol Phys 4:1111–1113.PubMedGoogle Scholar
  44. Fowler JR (1982) Fractionation of radiation dose in therapy, ASTR refresher course, Int J Radiat Oncol Biol Phys, Proc. Am Soc Ther Radiol, Orlando, Florida, 8 (Suppl 1):56, 1982.Google Scholar
  45. Fryer CJH, Fitzpatrick PJ, Rider WD, et al (1978) Radiation pneumonitis: experience following a large single dose of radiation, Int J Radiat Oncol Biol Phys 4:931–936.PubMedGoogle Scholar
  46. Gilbert RW, Kim JH, Posner JB (1978) Epidural spinal cord compression from metastatic tumor: diagnosis and treatment, Ann Neurol 3:40–51.PubMedGoogle Scholar
  47. Goff WF (1973) Intracordal polytef (Teflon) injection. Histologic study of two cases, Arch Otolaryngol 97:371–372.PubMedGoogle Scholar
  48. Graham EA, Singer JJ (1933) Successful removal of an entire lung for carcinoma of the bronchus, JAMA 101:1371–1374.Google Scholar
  49. Green J, Rubin P, Holzwasser G (1963) The experimental production of superior vena caval obstruction, Radiology 81:406–415.PubMedGoogle Scholar
  50. Green N, Kurohara SS, George FW, III (1971) Cancer of the lung: an in-depth analysis of prognostic factors, Cancer 28:1229–1233.PubMedGoogle Scholar
  51. Greenberg HS, Kim JH, Posner JB (1980) Epidural spinal cord compression from metastatic tumor: results with a new treatment protocol, Ann Neurol 8:361–366.PubMedGoogle Scholar
  52. Gross NJ (1977) Pulmonary effects of radiation therapy, Ann Intern Med 86:81–92.PubMedGoogle Scholar
  53. Guttman RJ (1965) Results of radiation therapy in patients with inoperable carcinoma of the lung whose status was established at exploratory thoracotomy, AJR 93:99–103.Google Scholar
  54. Hilaris BS, Luomanen RK, Manan GD, et al (1971) Interstitial irradiation of apical lung cancer, Radiology 99:655–660.PubMedGoogle Scholar
  55. Hilaris BS, Martini N, Batata M, et al (1975a) Interstitial irradiation for unresectable carcinoma of the lung, Ann Thorac Surg 20:491–500.PubMedGoogle Scholar
  56. Hilaris BS, Henschke UK (1975 b) General principles and techniques of interstitial brachytherapy. In: Hilaris BS (ed) Handbook of interstitial brachytherapy, chap 5, Publishing Sciences Grp Inc., Acton, Massachusetts.Google Scholar
  57. Hilaris BS, Martini N, Luomanen RK (1979) Endobronchial interstitial implantation, Clin Bull 9(1): 17–20.PubMedGoogle Scholar
  58. Jacobs L, Kinkel WR, Vincent RG (1977) “Silent” brain metastasis from lung carcinoma determined by computerized tomography, Arch Neurol 34:690–693.PubMedGoogle Scholar
  59. Jesse RH, Lindberg RD, Westbrook KC (1980) Neck nodes. In: Textbook of radiotherapy, 4th edn, Lea & Febiger, Philadelphia, p 339.Google Scholar
  60. Johnson RJR, Walton RJ, Lim ML, et al (1973) A randomized study on survival of bronchogenic carcinoma treated with conventional or short fractionation radiation, Clin Radiol 24:494–497.PubMedGoogle Scholar
  61. Kanji AM, Chao JH, Liebner EJ, et al (1980) Extrinsic compression of superior vena cava: an analysis of 41 patients, Int J Radiat Oncol Biol Phys 6:213–215.PubMedGoogle Scholar
  62. Kirsh MM, Sloan H (1981) Treatment of bronchogenic carcinoma with mediastinal metastases: a 15-year experience. In: Controversies in Surgical Oncology, pp 69–74.Google Scholar
  63. Kjaer M (1982) Radiotherapy of squamous, adeno- and large cell carcinoma of the lung, Cancer Treat Rev 9:1–20.PubMedGoogle Scholar
  64. Kline IK (1972) Cardiac lymphatic involvement by metastatic tumor, Cancer 29:799–808.PubMedGoogle Scholar
  65. Leddy ET, Moersch HJ (1940) Roentgen therapy for bronchogenic carcinoma, JAMA 115:2239–2242.Google Scholar
  66. Lewy RB, Matthews R (1965) Immediate temporary restoration of glottic valve function, Laryngoscope 75:1348–1351.PubMedGoogle Scholar
  67. Luomanen RKJ, Watson WL (1968) Autopsy findings. In: Watson, WL (ed) Lung Cancer: A study of five thousand Memorial Hospital cases. CV Mosby, Saint Louis, Mo., p 504.Google Scholar
  68. Mangini RJ (1982) Clinically important Cimetidine drug interactions, Clin Pharm 1:433–439.PubMedGoogle Scholar
  69. Marks RM, Sachar EJ (1973) Undertreatment of medical inpatients with narcotic analgesics, Ann Intern Med 78:173–181.PubMedGoogle Scholar
  70. Matthews MJ, Kanhowa S, Pickren J, et al (1973) Frequency of residual and metastatic tumor in patients undergoing curative surgical resection for lung cancer. Cancer Chemother Rep 4(2): 63–67.Google Scholar
  71. McBride CM, Brown BW, Thompson JR, et al (1983) Can patients with breast cancer be cured of their disease?, Cancer 51:938–945.PubMedGoogle Scholar
  72. Medical letter (1982) Drug treatment of cancer pain, Med Lett Drugs Ther 24(621): 95–96.Google Scholar
  73. Meoz RT, Hudgins PT, Wright A (1978) Effect of pulmonary function of split course radiation therapy for carcinoma of the lung, Rev Interam Radiol 3:(1): 15–19.PubMedGoogle Scholar
  74. Meyer JA (1973) Growth rate versus prognosis in resected primary bronchogenic carcinomas, Cancer 31: 1468–1472.PubMedGoogle Scholar
  75. Mira JG, Fullerton GD, Ezekiel J, et al (1982) Evaluation of computed tomography numbers for treatment planning of lung cancer, Int J Radiat Oncol Biol Phys 8:1625–1628.PubMedGoogle Scholar
  76. Morrison R, Deeley TJ, Cleland WP (1963) The treatment of carcinoma of the bronchus. A clinical trial to compare surgery and radiotherapy, Lancet 1:683–684.Google Scholar
  77. Mountain CF, Carr DT, Anderson WAD (1974) A system for the clinical staging of lung cancer, AJR 120:130–138.Google Scholar
  78. Muhm JR (1980) Editorial: Role of computed tomography in evaluation of intrathoracic lesions, J Thorac Cardio-vasc Surg 79:469–470.Google Scholar
  79. Neilsen ME Jr, Heaston DK, Dunnick NR, et al (1982) Preoperative CT evaluation of adrenal glands in non-small cell bronchogenic carcinoma, AJR 139:317–320.Google Scholar
  80. Nogeire C, Mincer F, Botstein C (1979) Long survival in patients with bronchogenic carcinoma complicated by superior vena caval obstruction, Chest 75:325–329.PubMedGoogle Scholar
  81. Occam’s razor, Webster’s New Collegiate Dictionary, G & C Merriam Company, Springfield, Mass, USA.Google Scholar
  82. Olson KB (1935) Primary carcinoma of the lung: a pathology study, Am J Pathol 11:449–468.PubMedGoogle Scholar
  83. Ormerod FC (1937) The pathology and treatment of carcinoma of the bronchus, J Laryngol Otol 52:733–745.Google Scholar
  84. Ormerod FC (1953) The late results of treatment, by interstitial radiation, of one hundred cases of carcinoma of the bronchus, J Laryngol Otol 67:406–416.PubMedGoogle Scholar
  85. Pallis CA, Louis S, Morgan RL (1961) Radiation myelopathy, Brain 84:460–479.PubMedGoogle Scholar
  86. Parish JM, Marschke RF, Dines DE, et al (1981) Etiologic considerations in superior vena cava syndrome. Mayo Clin Proc 56:407–413.PubMedGoogle Scholar
  87. Pater JL, Loeb M (1982) Nonanatomic prognostic factors in carcinoma of the lung. A multivariate analysis, Cancer 50:326–331.PubMedGoogle Scholar
  88. Percarpio B, Gray S (1979) Prolonged survival following the superior vena cava syndrome, Chest 75:639–640.PubMedGoogle Scholar
  89. Perez CA, Presant CA, Van Amburg AL III (1978) Management of superior vena cava syndrome, Semin Oncol 5:123–134.PubMedGoogle Scholar
  90. Perez CA, Stanley K, Rubin P, Kramer S, et al (1980) Patterns of tumor recurrence after definitive irradiation for inoperable non-oat cell carcinoma of the lung, Int J Radiat Oncol Biol Phys 6:987–994.PubMedGoogle Scholar
  91. Perez CA (1982) Editorial: Is postoperative irradiation indicated in carcinoma of the lung? Int J Radiat Oncol Biol Phys 8:2019–2022.PubMedGoogle Scholar
  92. Petrovich Z, Stanely K, Cox JD, Paig C (1981) Radiotherapy in the management of locally advanced lung cancer of all cell types: final report of randomized trial, Cancer 48:1335–1340.PubMedGoogle Scholar
  93. Posner JB (1977) Management of central nervous system metastases, Semin Oncol 4(1):81–91.PubMedGoogle Scholar
  94. Poste G, Doll J, Fidler IJ (1981) Interactions among clonal subpopulations affect stability of the metastatic pheno-type in polyclonal population of big melanoma cells, Proc Natl Acad Sci USA 78 (10): 6626–6630.Google Scholar
  95. Prasad SC, Pilepich MV, Perez CA (1981) Contribution of CT to quantative radiation therapy planning, AJR 136:123–128.PubMedGoogle Scholar
  96. Reagan TJ, Thomas JE, Colby MY Jr, (1968) Chronic progressive radiation myelopathy. Its clinical aspects and differential diagnosis, JAMA 203:106–110.PubMedGoogle Scholar
  97. Renner WD, O’Connor TP, Amtey SR et al (1977) The use of photogammetry in tissue compensator design, Part I: Photogrammetric determination of patient topography, Radiology 125:505–510, Part II: Experimental verification of compensator design, Radiology 125:511–516.PubMedGoogle Scholar
  98. Renner WD, O’Connor TP, Bermudez NM (1982) An electronic device for digitizing radiotherapy films for the construction of tissue compensators, Med Phys 9:910–916.PubMedGoogle Scholar
  99. Rosenblatt MB (1964) Lung cancer in the 19th century, Bull Hist of Med 38:395–425.Google Scholar
  100. Rubin P, Green J, Holzwasser G, et al (1963) Superior vena cava syndrome. Slow low-dose versus rapid high-dose schedules, Radiology 81:388–401.PubMedGoogle Scholar
  101. Rubin P (1969) Extradural spinal cord compression by tumor. Part I: Experimental production and treatment trials, Radiology 93:1243–1260.PubMedGoogle Scholar
  102. Rubin P, Casarett GW (1972) A direction for clinical radiation pathology: the tolerance dose. In: Vaeth JM (ed) Frontiers of Radiation Therapy and Oncology, vol 6, University Park Press, Baltimore, London, pp 1–16.Google Scholar
  103. Russell MH (1958) Contribution to symposium on presentation of results of cancer treatment, Seventh Intl Cancer Congress, London.Google Scholar
  104. Salazar OM, Scarantino CW, Rubin P, et al (1980) Total (half-body) systemic irradiation for occult metastases in non-small cell lung cancer, Cancer 46:1932–1944.PubMedGoogle Scholar
  105. Sandler MA, Pearlberg JL, Madrazo BL, et al (1982) Computed tomographic evaluation of the adrenal gland in the preoperative assessment of bronchogenic carcinoma, Radiology 145:733–736.PubMedGoogle Scholar
  106. Schneider JS, Edwards JE (1979) Irradiation-induced pericarditis, Chest 75:560–564.PubMedGoogle Scholar
  107. Sealy R, Lagakos S, Barkley T, et al (1982) Radiotherapy of regional epidermoid carcinoma of the lung: a study in fractionation, Cancer 49:1338–1345.PubMedGoogle Scholar
  108. Selawry OS, Hansen H (1973) Lung cancer. In: Holland JF, Frei E (ed) Cancer Medicine, chap XXIII, Lea & Febiger, Philadelphia pp 1473–1518.Google Scholar
  109. Seydel HG, Kutcher GJ, Steiner RM, et al (1980) Computed tomography in planning radiation therapy for bronchogenic carcinoma, Int J Radiat Oncol Biol Phys 6:601–606.PubMedGoogle Scholar
  110. Shah K, Olson MH, Ray P, et al (1981) Comparison of dose-time-fractionation schemes in non-oat cell lung cancer, Cancer 48:1127–1132.PubMedGoogle Scholar
  111. Shankar PS (1980) Split-course radiation therapy: effects on pulmonary function in patients with bronchogenic carcinoma, J Am Geriatr Soc 28:547–549.PubMedGoogle Scholar
  112. Sherman DM, Weichselbaum R, Hellman S (1981) The characteristics of long-term survivors of lung cancer treated with radiation, Cancer 47:2575–2580.PubMedGoogle Scholar
  113. Silverberg E (1983) Cancer statistics, CA 33(1): 9–25.PubMedGoogle Scholar
  114. Slawson RG, Prempree T, Viravathana T, et al (1981) Radiation therapy for superior vena cava syndrome due to lung cancer, Md State Med J 30(11):68–70.PubMedGoogle Scholar
  115. Smart J (1966) Can lung cancer be cured by radiation alone?, JAMA 195:1034–1035.PubMedGoogle Scholar
  116. Sontag S (1979) Illness as metaphor, Farrar, Straus and Giroux, New York.Google Scholar
  117. Spjut HJ, Mateo LE (1965) Recurrent and metastatic carcinoma in surgically treated carcinoma of the lung, Cancer 18:1462–1466.PubMedGoogle Scholar
  118. Stewart JR, Fajardo LF (1971) Radiation induced heart disease. Clinical and experimental aspects, Radiol Clin North Am 9:511–531.PubMedGoogle Scholar
  119. Straus MJ (1974) The growth characteristics of lung cancer and its application to treatment design, Semin Oncol 1:167–173.PubMedGoogle Scholar
  120. Tong D, Gillick L, Hendrickson FR (1982) The palliation of symptomatic osseous metastases. Final results of the study by the Radiation Therapy Oncology Group, Cancer 50:893–899.PubMedGoogle Scholar
  121. Törmä T (1957) Malignant tumors of the spine and the spinal extradural space. A study of 250 histologically verified cases, Acta Chir Scand [Suppl] 225:1–138.Google Scholar
  122. Twycross RG (1979) Advances in pain research and therapy. In: Bonica JJ, Ventafridda V (ed) Overview of analgesia, vol 2, Raven Press, New York, pp 617–633.Google Scholar
  123. Ushio Y, Posner R, Posner JB, et al (1977) Experimentalspinal cord compression by epidural neoplasms, Neurology 27:422–429.PubMedGoogle Scholar
  124. Van Houtte P, Rocmans P, Smetz P, et al (1980) Postoperative radiation therapy in lung cancer: a controlled trial after resection of curative design, Int J Radiat Oncol Biol Phys 6:983–986.PubMedGoogle Scholar
  125. Wara WU, Phillips TL, Margolis LW, et al (1973) Radiation pneumonitis: a new approach to the deviation of time dose factors, Cancer 32:547–552.PubMedGoogle Scholar
  126. West J, Maor M (1980) Intracranial metastases: behavioral patterns related to primary site and results of treatment by whole brain irradiation, Int J Radiat Oncol Biol Phys 6:11–15.PubMedGoogle Scholar
  127. White KT, Fleming TR, Laws ER Jr (1981) Single metastasis to the brain. Surgical treatment in 122 consecutive patients, Mayo Clin Proc 56:424–428.PubMedGoogle Scholar
  128. Zylak CJ, Pallie W, Jackson R (1982) Correlative anatomy and computed tomography: a module on the medias terms, Radiographics 2(4): 555–592.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1985

Authors and Affiliations

  • Thomas O’Connor
    • 1
  1. 1.Community HospitalsIndianapolisUSA

Personalised recommendations